Category: Class 11 Chemistry Objective Questions

250+ TOP MCQs on Position of Hydrogen in the Periodic Table and Answers

Chemistry Multiple Choice Questions on “Position of Hydrogen in the Periodic Table”.

1. The element that is known as Rogue element is ________
a) beryllium
b) hydrogen
c) helium
d) lithium
Answer: b
Clarification: Hydrogen resembles with alkali metals as well as halogens at the same time it differs from both and certain characteristics, that is why hydrogen is called a Rogue Element. Finally, it’s been placed in the first group.

2. Which of the following element is an alkali as well as halogen?
a) hydrogen
b) sodium
c) chlorine
d) magnesium
Answer: a
Clarification: Hydrogen is an alkali metal as well as a halogen because of its outer shell configuration as well as its high electronegative character, no other element has a type of duel characteristic in the periodic table.

3. Which of the following is hydrogen’s electronic configuration?
a) 1s1
b) 1s2
c) 2s1
d) 2s2
Answer: a
Clarification: The electronic configuration of hydrogen is 1s1, as it has only one Proton. It belongs to the first group and is ready to gain one electron in order to become a noble gas like helium which is next to it.

4. The atomic number of hydrogen is 1.
a) true
b) false
Answer: a
Clarification: Atomic number of an element represents the number of protons in that particular element. Here as hydrogen has only one Proton, its atomic number is considered to be one, so the above statement is true.

5. Hydrogen is a ___________________
a) metal
b) metalloid
c) non-metal
d) solid
Answer: c
Clarification: Hydrogen is a nonmetal denoted by the symbol “H”, but it is placed in the first group, which consists of metals. This is because of the outer shell configuration of hydrogen and that it’s valency is 1. It’s highly electronegative in nature.

6. Hydrogen is the 1st element. The elements in the periodic table are arranged with respect to their __________
a) atomic numbers
b) molecular weights
c) atmospheric abundance
d) physical state
Answer: a
Clarification: We all know that the elements in the periodic table are arranged according to their atomic numbers and atomic numbers are nothing but the number of protons in that element. So hydrogen takes the first place.

7. Hydrogen has _____________ ionization enthalpy.
a) high
b) low
c) zero
d) no
Answer: a
Clarification: Though hydrogen is placed in the first group which is of alkali metals, it has a very high ionization enthalpy this is because it has a characteristic of a halogen as well. We can say that hydrogen is an alkali metal and a halogen at a time.

8. The property of hydrogen of forming diatomic molecule is from ______________
a) halogen
b) alkali metal
c) noble gas
d) d-block
Answer: a
Clarification: As we know that hydrogen is an alkali metal as well as a halogen. It has properties of both alkali metals and halogens, the property of formation of a diatomic molecule is from halogens, but not from alkali metals.

9. H+ Ion exist freely.
a) true
b) false
Answer: b
Clarification: The loss of electrons from hydrogen atom results in the hydrogen nucleus that is H+ of the size 1.5 x 10-3 pm and it is extremely small when compared to a normal at atomic and ionic sizes that are around 50 to 200 pm.

10. Reactivity of hydrogen is ______________ compared to halogens.
a) high
b) low
c) zero
d) negative
Answer: b
Clarification: Though hydrogen has many properties of halogens, in terms of reactivity it shows very low similarity when compared to halogens. This is one of the reasons, it’s probably not placed in halogens, but in alkali metals.

250+ TOP MCQs on p-Block Elements – Uses of Boron and Aluminium and their Compounds and Answers

This set of Chemistry Question Papers for NEET Exam on “p-Block Elements – Uses of Boron and Aluminium and their Compounds”.

1. What is ammonal?
a) a mixture of aluminium powder with ammonium nitrite
b) a mixture of aluminium powder with ammonium nitrate
c) a mixture of aluminium powder with ammonium sulphate
d) a mixture of aluminium powder with ammonium chloride
Answer: b
Clarification: A mixture of aluminium powder with ammonium nitrate is called ammonal and is used in bombs with a ratio of 5:95. Here the aluminium acts as a fuel and ammonium nitrate as an oxidizer, it was first used in the year 1916 by the britishers near mines.

2. Which of the following material is used for making fireproof clothes?
a) Aluminium chloride
b) Aluminium oxide
c) Aluminium nitrate
d) Aluminium sulphate
Answer: d
Clarification: Aluminium sulphate which is given by the chemical formula Al2(SO4)3 is used for making fireproof clothes and it is also used as a fire fighting foam. Aluminium sulphate is also used as an antiseptic, astringent and also as a modern in dyeing textiles.

3. Which of the following is not a use of Boron?
a) silver paints
b) bulletproof vest
c) in nuclear reactors
d) making of boron fibres
Answer: a
Clarification: There are many applications of boron like heat resistant glasses, glass wool, fibreglass, flux for soldering metals, for heat, scratch and stain resistant glazed coating to earth and wears and as a constituent of medical soaps. It is also used and the making of Boron fibres, bulletproof vest making and also and nuclear reactions in order to absorb neutrons.

4. Boron is used as a ______________
a) double insulator
b) semiconductor
c) insulator
d) conductor
Answer: b
Clarification: Yes, Boron is used as a semiconductor and also Boron Steel rods are used for controlling the nuclear reactions. Boron is used as a dopant for semiconductors such as Silicon and Germanium. Pure Boron is a black, lustrous semiconductor.

5. Which of the following is not a use of orthoboric acid?
a) painting
b) antiseptic
c) eye lotion
d) food preservative
Answer: a
Clarification: Orthoboric acid which is given by the chemical formula H3BO3 is used as an antiseptic and eye lotion under the name boric lotion and it is also used as a food preservative. The boric lotion is a saturated solution of 4% boric acid in water.

6. Which of the following is used as a catalyst in Friedel craft reaction?
a) cement
b) boron
c) anhydrous aluminium chloride
d) borax
Answer: c
Clarification: Friedel crafts reactions are the reactions in which substituents are added to the aromatic rings. There are two types of friedel craft reactions namely alkylation and acylation. Anhydrous aluminium chloride is used as a catalyst in these Friedel craft reactions.

7. What is the chemical formula of alumina and anhydrous aluminium chloride?
a) Al2O3, AlCl
b) Al2O3, AlCl3
c) Al2O, AlCl3
d) AlO3, AlCl3
Answer: b
Clarification: The chemical formula of alumina is Al2O3 and that of anhydrous aluminium chloride is AlCl3. Alumina is nothing but aluminium oxide. Anhydrous aluminium chloride is prepared by heating a mixture of alumina and carbon in a current of dry chlorine.

8. Aluminium oxide as otherwise called as ______________
a) aluminium sulphate
b) alumina
c) alum
d) aluminium
Answer: b
Clarification: Alumina is also known as aluminium oxide and it is the most stable compound of aluminium that occurs in nature as colourless corundum and several coloured oxides, like ruby, topaz, sapphire, and emerald, these are used as precious stones.

9. Alum is a double sulphate.
a) true
b) false
Answer: a
Clarification: The term alum is given to double sulphates of the type X2SO4.Y2(SO4)3.24H2O where, X represents a monovalent cation such as sodium ion, potassium ion and ammonium while why is a trivalent cation such as aluminium 3 +, chromium 3 +, ferrous 3 + and Cobalt 3 +. Lithium-ion does not form alum.

10. Which of the following is not an alum?
a) covalent alum
b) Potash alum
c) ammonium alum
d) sodium alum
Answer: a
Clarification: K2SO4.Al2(SO4)3.24H2O, Na2SO4.Al2(SO4)3.24H2O, (NH4)2SO4.Al2(SO4)3.24H2O and (NH4)2SO4.Fe2(SO4)3.24H2O are respective chemical formulae of Potash alum, sodium alum, ammonium alum and ferric alum.

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250+ TOP MCQs on Environmental Pollution and Answers

Chemistry Multiple Choice Questions on “Environmental Pollution”.

1. A substance, which causes pollution, is known as which of the following?
a) Pollutant
b) Carcinogen
c) Polluting element
d) Irritant
Answer: a
Clarification: A substance, causing pollution, is called as a pollutant. Pollutants can be solid, liquid, or gaseous substances present in greater concentrations than in natural abundance and are produced due to human activities or due to natural happenings. Carcinogens are substances, if exposed to, which can cause cancer. Irritants normally cause irritations to skin.

2. Identify the degradable pollutant from the following.
a) Chemicals
b) Metals
c) Discarded vegetables
d) Plastic
Answer: c
Clarification: Discarded vegetables are degradable pollutants. Since they are organic, they can be rapidly broken down by micro-organisms through natural processes. Chemicals, metals, and plastics are inorganic and they will slowly degrade, thereby, remaining in an unchanged form in the environment for many decades.

3. What is the full form of DDT?
a) Diphenyldichlorotrichloroethane
b) Dichlorodiphenyltrichloroethane
c) Dichlorodiphenyltriphenylethane
d) Dichlorodiphenyltrichloroethene
Answer: b

Clarification: The full form of DDT is dichlorodiphenyltrichloroethane. It is a colorless, tasteless, and almost odorless crystalline chemical compound. It was originally developed as an insecticide, but then, its use was stopped due to its harmful effect on environment as well as on the living organisms. If exposed to high concentrations, it can cause vomiting, seizures or tremors in human beings.

4. An average human being requires nearly 12-15 times more air than the food.
a) True
b) False
Answer: a
Clarification: An average human being requires nearly 12-15 times more air than the food. So, even small amounts of pollutants in the air become significant compared to similar levels present in the food. Therefore, the amount of people suffering various diseases due to contaminants in air is more than that suffering due to contaminants in food.

5. Which of the following is not a constituent of DDT?
a) Carbon
b) Fluorine
c) Chlorine
d) Hydrogen
Answer: b
Clarification: Fluorine is not a constituent of DDT. DDT is dichlorodiphenyltrichloroethane which has a chemical formula of C14H9Cl5. Therefore, DDT does not contain fluorine, which is evident from the chemical formula. It also contains impurities in small quantities, i.e., about 15% of its composition. The major component which comprises of 77% of the substance is its para isomer.

250+ TOP MCQs on Stoichiometry and Stoichiometric Calculations and Answers

Chemistry Multiple Choice Questions on “Stoichiometry and Stoichiometric Calculations”.

1. In a particular reaction, one of the reactants limits the number of products formed. That is called as _______
a) Limiting reagent
b) Limiting product
c) Excessive reagent
d) Excessive reactant
Answer: a
Clarification: Though the other substances are excess in amount than the required, each and every reactant needs to be in a fixed ratio to attain the desired product. So, thereby, the reactant that limits the quantity of the product formed is called limiting reagent and this reactant gets consumed first completely.

2. Which of the following is not true regarding balanced chemical equations?
a) They contain the same number of atoms on each side
b) Electrons are also balanced
c) An equal number of molecules on both the side
d) Follows the law of conservation of mass
Answer: c
Clarification: A balanced reaction may not have an equal number of molecules on both the sides, because molecules may combine into one or a single molecule may breakdown into two or more. IT can disassociate or undergo double decomposition.

3. Which of the given reactions are counted as balanced reactions?
a) H2 + O2 → 2H2O
b) 4Al + 3O2 → 2Al2O3
c) Mg(OH)2 + 2HNO3 → 2Mg(NO3)2 + 2H2O
d) N2 + 3H2 → NH3
Answer: b
Clarification: 4Al + 3O2 → 2Al2O3 is a balanced reaction because the number of atoms of different elements on both sides is equal. The correctly balanced equations of the rest are 2H2 + O2 → 2H2O; Mg(OH)2 + 2HNO3 → Mg(NO3)2 + 2H2O and N2 + 3H2 → 2NH3.

4. What is the amount of water produced when 8g of hydrogen is reacted with 32g of oxygen?
a) 2moles
b) 1mole
c) 3 moles
d) 0.5mole
Answer: a
Clarification: The chemical equation of water formation is 2H2 + O2 → 2H2O. Though we have 8g of hydrogen, here oxygen is the limiting reagent. So the only 4g of hydrogen can be used to produce water i.e. 36g of water. That is 2 moles.

5. Calculate the mass percent of magnesium in the formation of magnesium oxide.
a) 0.3
b) 1.5
c) 0.67
d) 0.6
Answer: d
Clarification: The chemical equation of formation of magnesium oxide is 2 Mg(s) + O2(g) ® 2MgO(s). The formula for calculation of mass percent is (mass of solute/mass of solution) x 100. Therefore 2(24)/2(24+16) = 0.6.

6. A and B are two solutions that are mixed. Calculate the resultant solution’s molarity.

Initial Solutions Molarity Volume
A 1.3 100ml
B 0.8 500ml

a) 0.8 mol/L
b) 0.88 mol/L
c) 1.3 mol/L
d) 1.05 mol/L
Answer: b
Clarification: When two solutions are combined, the resultant molarity is M1V1 + M2V2/V1 + V2. Consider M1 = 1.3, M2 = 0.8, V1 = 100ml and V2 = 500ml. Now resultant molarity = 1.3(100) + 0.8(500)/100 + 500 = 0.88 mol/L.

7. A solution contains 8 moles of solute and the mass of the solution is 4 kg. What’s the molality of this solution?
a) 5 mol/kg
b) 8 mol/kg
c) 4 mol/kg
d) 0.5 mol/kg
Answer: d
Clarification: Molality of a solution is given y the formula; molality = number of moles of the solute/mass of the solution. So here the number of moles is 8 and the mass of the solution is 4 kg. Molality is 8/4 = 0.5 mol/kg.

8. In a container, there are 4 moles of nitrogen, 3 moles of oxygen and 7 moles of hydrogen; find out the mole fraction of oxygen in this reaction.
a) 0.2143
b) 0.2142
c) 0.1234
d) 0.2434
Answer: a
Clarification: Mole fraction of a substance is given by the formula: Mole fraction = No. of moles of that substances/No. of total moles of solution. Mole fraction of oxygen here = 3/4 + 3 + 7 = 3/14 = 0.2143.

9. Find the amount of carbon dioxide produced by the combustion of 20g of methane.
a) 44g
b) 20g
c) 66g
d) 22g
Answer: c
Clarification: The chemical balanced equation for combustion of methane is CH4(g) + 2O2(g) →CO2(g) + 2H2O(g). From the above equation, 1 mole of methane gives 1 mole of carbon dioxide. But 20g of methane = 1.25 moles, therefore it gives 1.25 moles of carbon dioxide = 44(1.5) = 66g.

10. What’s the balanced equation of CO2 + H2O → C6H12O6 + O2?
a) CO2 + H2O → C6H12O6 + O2
b) 6 CO2 + 6 H2O → C6H12O6 + 6 O2
c) 6 CO2 + 6 H2O → C6H12O6 + 2 O2
d) 3 CO2 + 2H2O → C6H12O6 + O2
Answer: b
Clarification: 6 CO2 + 6 H2O → C6H12O6 + 6 O2 is the balanced equation because the number of atoms of different elements is the same on both sides. Rest of them do not have an equal number of atoms of different elements on both sides.

250+ TOP MCQs on Valence Shell Electron Pair Repulsion (VSEPR) Theory and Answers

Chemistry Multiple Choice Questions on “Valence Shell Electron Pair Repulsion (VSEPR) Theory”.

1. Which of the following is correct regarding repulsive interaction?
a) Lone pair-Lone pair is greater than Lone pair-Bond pair is greater than Bond pair-Bond pair
b) Lone pair-Lone pair is less than Lone pair-Bond pair is less than Bond pair-Bond pair
c) Lone pair-Bond pair is greater than Lone pair-Lone pair is greater than Bond pair-Bond pair
d) Lone pair-Lone pair is greater than Lone pair-Bond pair is less than Bond pair-Bond pair

Answer: a
Clarification: The repulsive interactions follow the above order. The lone pairs are localized on the central atom, each bonded pair is shared between two atoms. So, the lone pair electrons in a molecule occupy more space as compared to the bonding pairs of electrons.

2. The shape of the molecule depends on the _______
a) adjacent atom
b) valence electrons
c) surroundings
d) atmosphere

Answer: b
Clarification: As the postulate of Valence Shell Electron Pair Repulsion Theory (VSEPR), the shape of the molecule depends on the number of valence shell electron pairs around the atom (both bonded and non-bonded).

3. The shape a molecule occupies allows to minimize repulsions among them and maximize the space between them.
a) True
b) False

Answer: a
Clarification: As the postulate of Valence Shell Electron Pair Repulsion Theory (VSEPR), a molecule tends to form a shape or orientation that has little repulsion comparatively and the higher distance between the electron pairs comparatively.

4. What is the shape of the molecule NH3?
a) Square pyramidal
b) V-shape
c) Triagonal pyramidal
d) Tetrahedral

Answer: c
Clarification: The molecule NH3 has a lone pair and 3 bond pairs. As we know that the repulsion order is as follows: Lone pair-Lone pair is greater than Lone pair-Bond pair is greater than Bond pair-Bond pair. So the shape of molecule NH3 is trigonal pyramidal, where the lone pair is away from the 3 bond pairs.

5. How many orbitals are included in sp3d hybridization?
a) 5
b) 4
c) 3
d) 6

Answer: a
Clarification: The concept of mixing of atomic orbitals and formation of new hybridized atomic orbitals for the pairing of electrons through chemical bonds. Therefore sp3d hybridization included 5 orbitals namely 1 s-orbital, 3 p-orbitals, and 1 d-orbital.

6. A double bond is made up of __________
a) Two sigma bonds
b) Two pi bonds
c) One sigma and one pi bond
d) Two sigmas and one pi bond

Answer: c
Clarification: A double bond is formed chemically between two atoms that involve the bonding of four electrons. A double bond is formed with one sigma and one pi bond. The formation of molecules like ethane, oxygen involve double bonds.

7. Which of the following molecules geometry is true?
a) BrF5 – Triagonal pyramidal
b) ClF3 – T-shape
c) PCl5 – See-saw
d) SF4 – Triagonal bipyramidal

Answer: b
Clarification: The molecule ClF5 has T-shape as it 3 bonding pairs and 2 lone pairs, so it’s true. The molecules BrF5, PCl5, and SF4 have the shapes square pyramidal, trigonal bipyramidal and see-saw respectively.

8. What is the shape of water?
a) Triagonal
b) Triagonal bipyramidal
c) Bent
d) Square planar

Answer: c
Clarification: The water molecule H-O-H has an arrangement of electrons in a tetrahedral. As it contains two bond pairs and lone pairs in the form of the molecule of type AB3E2, it’s shape is bent i.e. neglecting the lone pairs.

9. The angle between two bonds in a linear molecule is _______
a) 108°
b) 180°
c) 74.5°
d) 90°

Answer: b
Clarification: A linear molecule has a hybridization sp, in which the bonds between the central atom and other atoms are separated by 180°. For example, let’s take carbon dioxide, it’s shape is given by O=C=O.

250+ TOP MCQs on Equilibrium in Chemical Processes – Dynamic Equilibrium and Answers

Chemistry Multiple Choice Questions on “Equilibrium in Chemical Processes – Dynamic Equilibrium”.

1. What does the dotted curve in the diagram given below represent?
chemistry-questions-answers-equilibrium-chemical-processes-dynamic-equilibrium-q1
a) concentration of reactants
b) equilibrium constant
c) concentration of products
d) concentration of catalyst
Answer: c
Clarification: The dotted curve in the above diagram the concentration of products as it is increasing with time and the attainment of equilibrium, the Strait curve is a concentration of reactants as it is decreasing as the reaction proceeds.

2. Synthesis of ammonia occurs through __________
a) Haber’s process
b) The carbon cycle
c) Nitrogen cycle
d) Hydrogen cycle
Answer: a
Clarification: Haber’s process allows nitrogen from the air to combine with hydrogen in order to form ammonia, this process is reversible and exothermic. This process occurs at high temperatures and a catalyst is a form of iron.

3. Equilibrium can be attained only from one side.
a) true
b) false
Answer: b
Clarification: An equilibrium can be obtained from both sides this is because a chemical reaction that reaches a state of dynamic equilibrium in which there are equal rates of forwarding and backward reactions and there is no net change in composition.

4. At dynamic equilibrium the concentration of both the reactants and products are ____________
a) equal
b) not equal
c) cannot predict
d) sometimes equal sometimes not equal
Answer: b
Clarification: A dynamic equilibrium in a chemical reaction, both forward and backward rates are always equal. As the reaction occurs the concentration of product increases and the concentration of reactants decrease at equilibrium they are not equal.

5. In which of the following conditions do you think the rates of both forward and backward reactions are the same?
a) unstable equilibrium
b) not in an equilibrium
c) the beginning of a reaction
d) equilibrium
Answer: d
Clarification: In a chemical reaction a state comes when both the forward and reverse reactions occur at the same rate and this state is known as equilibrium. At the beginning of the reaction, the rate of the Forward reaction is higher than the rate of backward reaction.

6. What is the reverse reaction of s of water?
a) conversion into ice
b) conversion into steam
c) conversion into water
d) equilibria
Answer: c
Clarification: The process of solidifying of water is nothing but the formation of ice that is a condensation of water the reverse reaction of condensation of water is the melting of water, that is the formation of water from ice.

7. Dynamic equilibrium mainly concerns about _______________
a) spontaneous reactions
b) nonspontaneous reactions
c) reversible reactions
d) Irreversible reactions
Answer: d
Clarification: In case of dynamic equilibrium, the ratio of reactants and products changes. The net change equals zero, as there is no net movement of particles. The formation of the reactants is equal to the formation of products here in dynamic equilibrium.

8. At which of the following temperatures water is a dynamic equilibrium with ice?
a) 0 Kelvin
b) zero degree centigrade
c) zero degree Fahrenheit
d) 100 Kelvin
Answer: b
Clarification: Water is a dynamic equilibrium with ice at the freezing point of water that is zero degrees centigrade, 273 Kelvin and 32-degree Fahrenheit. Because at zero degrees centigrade the phase transition occurs.

9. When a chemical reaction is written the products are written on the _____________
a) left side
b) right side
c) either left side or right side
d) depends on the chemicals present
Answer: b
Clarification: When a chemical reaction is written, the reactants are written on the left side and the products are written on the right side, while both parts of the reaction are joined by an arrow mark (→).

10. Equilibrium of a reaction depends on the concentration of reactants.
a) true
b) false
Answer: b
Clarification: In a chemical reaction equilibrium does not depend on the concentration of reactants as well as a concentration of products. Equilibrium is attained when the rates of both forward and backward reactions are equal.