Inorganic Chemistry - Past JEE - True or False Type questions

State whether the following statements are true or false

1. Red phosphorus is less volatile than white phosphorus because the former has a tetrahedral structure. (1982)

2. MgCl2.6H2O on heating gives anhydrous MgCl2. (1982)

3. When PbO2 reacts with a dilute acid, it gives hydrogen peroxide. (1982)

4. Copper metal reduces Fe²⁺ in an acid medium. (1982)

5. Silver fluoride is fairly soluble in water. (1982)

6. Dilute HCl oxidizes metallic Fe to Fe²⁺. (1983)

7. In an aqueous solution chlorine is a stronger oxidizing agent than fluorine. (1984)

8. Silver chloride is more soluble in very concentrated sodium chloride solution than in pure water. (1984)

9. Solubility of sodium hydroxide increases with increase in temperature. (1985)

10. Sodium when burnt in excess of oxygen gives sodium oxide. (1987).

11. Both potassium ferrocyanide and potassium ferricyanide are diamagnetic. (1989)

12. Cu⁺ disproportionates to Cu²⁺. (1991)

13. Nitrous oxide, though an odd electron molecule, is diamagnetic in liquid state. (1991)

14. Diamond is harder than graphite. (1993)

15. The basic nature of the hydroxides of Group 13 (Gr. III B) decreases progressively down the group. (1993)

16. The tendency for catenation is much higher for C than for Si. (1993)

17. HBr is stronger acid than HI because of hydrogen bonding. (1993)

Answers sometime later

Gaseous, Liquid, Solid State - True or False Type Questions

1. When a liquid and its vapour are in equilibrium and the pressure is suddenly decreased, cooling occurs. (JEE 1984)

True

Reason: The decrease in pressure results in further evaporation of the liquid into gaseous phase. The energy required for this is realized from the liquid itself which causes a decrease in temperature.

2. Kinetic energy of molecules is zero at 0°C. (JEE 1985)

Ans: False

The equation relating energy of molecules to temperature is in absolute temperature and not centigrade temperature.

3. A gas in a closed container will exert much higher pressure due to gravity at the bottom than at the top. (JEE 1985)

False.

It is equal in all directions.

4. Heat capacity of a diatomic gas is higher than that of a monatomic gas. (JEE 1985)
True

Diatomic gas has translational, rotational, and vibrational energies. Monatomic gas has only translational energy.

5. In the van der Waals equation,

[p + n²a/V²][V-nb] = nRT

the constant ‘a’ reflects the actual volume of the gas molecules.

False

Reason: In the equation ‘a’ is a measure of the forces of attraction between gaseous molecules and b is a measure of effective volume occupied the molecules of 1 mol of a gas.

Atomic Structure - True or False Type Questions

1. The outer electronic configuration of the ground state chromium atom is 3d⁴4s². (JEE 1982)

False

Chromium atomic number is 24.
Its our electronic configuration is 3d⁵4s² .

2. The energy of the electron in the 3d-orbital is less than that in the 4s-orbital in the hydrogen atom. (JEE 1983)

Ans: True. (Think what is the explanation)

Periodic Properties - True or False Type Questions

1. Dispositive zinc exhibits paramagnetism due to loss of two electrons from 3d-orbital of neutral atom. (JEE 1987)

False.

Reason: Zn²⁺ exhibits diamagnetism. Formation of the ion involves loss of two electrons from 4s orbital. The resultant configuration of 10 electrons in 3d orbital does not have unpaired electrons. So it exhibits diamagnetism.

2. In Group IA of alkali metals, the ionization potential decreases down the group. Therefore lithium is a poor reducing agent.

False

Reducing strength is determined by the negative of reduction potential (i.e., oxidation potential) and not by the ionization potential. Lithium is the strongest reducing agent among alkali metals.

3. Both potassium ferrocyanide and potassium ferricyanide are diamagnetic. (JEE 1989)

False

Potassium ferrocyanide is diamagnetic (no unpaired electron) while potassium ferricyanide is paramagnetic (one unpaired electron)

4. The presence of polar bonds in a polyatomic molecule suggests that the molecule has non-zero dipole moment. (JEE 1990)

False

There are polyatomic molecules with polar bonds that have zero dipole moment due to symmetric arrangement of polar bonds.

5. The decreasing order of electron affinity of F,Cl, Br is F>Cl>Br. (JEE 1993)

False

The order is Cl>F>Br. Due to the small size in F atom there is larger electronic repulsion. Hence electron affinity is more in Cl than in F.


6. The basic nature of hydroxides of Group13 (Gr. III B) decreases progressively down the group. (JEE 1993)

False

Basic nature increases as the element becomes more metallic. As one goes down the group metallic character increases.

Chemical Bonding - True or False Type

1. Linear overlap of two atomic p-orbitals leads to a sigma bond. (JEE 1983)

True

2. The H-N-H bond angle in NH3 is greater than the H-As-H bond angle in AsH3.

True

Reason: Repulsion is more in NH3 which makes the bond angle greater than in AsH3.

3. All molecules with polar bonds have dipole moment. (JEE 1985)

False.

Reason; If symmetrical arrangement of atoms is there, there is no dipole moment. Example CCl4.

4. SnCl2 is nonlinear molecule. (JEE 1985)
True

There is a lone pair in the bond. Due to repulsion between Lone pair and bonding pair, the bond angle less than 180°.

5. sp² hybrid orbitals have equal s and p character.

False

sp² hybrid use one s orbital and 2 p orbital for hydridisation. Hence sp² hybrid orbitals have 1/3 s character and 2/3 p character.

6. All the Al-Cl bonds in Al2Cl6 are equivalent. (JEE 1989)

False

The terminal Al-Cl bonds are different from the bridge Al-Cl bonds.

7. Nitric oxide, though an odd electron molecule, is diamagnetic in liquid state. (JEE 1991)

False

In liquid state, some dimerization takes place, but it is only partial. So it is still paramagnetic only.

8. Dipole moment of CH3F is greater than CH3Cl. (JEE 1993)
False

Bond distance is more in CH3Cl and hence more dipole moment.
Dipole moment = charge * distance

Energetics - True or False Types

1. First law of thermodynamics is not adequate in predicting the direction of a process.
(JEE 1982)

True

First law only says increase in internal energy of a system is due to heat transferred to the system and work done on the system. It does not predict the direction of a process.

Chemical Equilibrium - True or False Type Questions

1. If equilibrium constant for the reaction A2 + B2 ↔ 2AB, is K, then for the backward reaction AB ↔ ½ A2 + ½ B2, the equilibrium constant is 1/K. (JEE 1984)

Answer: False

Reason: For A2 + B2 ↔ 2AB,
K = [AB] ²/[A2][B2]

For AB ↔ ½ A2 + ½ B2 equilibrium constant is

= [A2] ^1/2[B2] ^1/2/[AB]

This is not equal to 1/K.

2. Solubility of sodium hydroxide increases with increase in temperature. (JEE 1985).

Answer: False

3. From the solution containing copper (+2) and zinc (+2) ions , copper can be selectively precipitated using sodium sulphide. (JEE 1987)

False

Na2S will produce an alkaline solution, both copper (+2) and zinc (+2) ions would be precipitated.

4. The rate of exothermic reaction increases with increasing temperature. (JEE 1990).

Answer: True
Reason: In general, rate of a reaction increases with increase in temperature which is due to increase in the rate constant of the reaction. As per the Arrhenius equation relating k and T, as temperature increases k increases. (Note: At equilibrium if the temperature is increased, for an exothermic reaction the equilibrium shifts leftward).

Electrochemistry - True or False Questions

1. The dependence of electrode potential for the electrode Mⁿ⁺ |M with conetration under STP conditions is given by the expression:

E = E° + 0.0591 V/n * log₁₀[Mⁿ⁺ |]

(JEE 1993)

False

The factor 0.0591 is applicable when the temperature is 298 K and not 273 K.

Chemical Kinetics - True or False Type Questions

1. For a first order reaction, the rate of the reaction doubles as the concentration of the reactant(s) doubles. (1986)

Answer: True

Reason: For a first order reaction r = k[A].
Where r = rate of reaction
K = reaction constant
[A] = molar concentration of reactant
Hence if concentration doubles r also is doubled,.

2. Catalyst makes reaction more exothermic. (JEE 1987)

Ans: False
Catalyst does not affect the enthalpy of reaction. It affects only the rate of reaction.

Nuclear Chemistry - True - False Type Questions

1. Gamma rays are electromagnetic radiations of wavelengths of 10^-6 to 10^-5 cm. (1983)

Ans: False

2. In β-emission from a nuclues the atomic number of the daughter element decreases by one. (JEE 1990).

Answer: False

In β-emission, number of protons in the nucleus goes up by one.

3. In a given electric field, β-particles are deflected more than α-particles having larger charge. (JEE 1993)

True

The deflection of the particle depends on the acceleration produced in it. The acceleration depends on the force and mass. Thus, in case of electric field it depends on the e/m of the particles. For β-particles, e/m is larger than α-particles because electrons are very very light than He⁺ species. So charge on helium particle is only twice high but mass is very very high.

Chemical Bonding - 12 - True or False type Questions

State whether the following statements are True or False.

1. Linear overlap of two atomic p-orbitals leads to a sigma bond. (JEE 1983)

True

2. The H-N-H bond angle in NH3 is greater than the H-As-H bond angle in AsH3. (JEE 1984)

True. Repulsion among bonds is more in NH3 and it makes bond angle greater.

3. All molecules with polar bonds have dipole moment. (JEE 1985)

False. Symmetrical molecules will have zero dipole moment.

4. SnCl2 is nonlinear molecule (JEE 1985)

True

5. sp² hybrid orbitals have equal s- and p- character (JEE 1987)

False. One third s and two thirds p.


The presence of polar bonds in a polyatomic molecules suggests that molecule has non-zero dipole moment (JEE 1990)

False. Some polyatomic molecules having polar bonds have zero dipole moment.


H2O molecule is linear. (JEE 1993)

False. It is V-shaped.

The dipole moment of CH3F is greater than that of CH3Cl. (JEE 1993)

False. Dipole moment in CH3F is less than CH3Cl as bond length is shorter in CH3F. Remember the definition of dipole moment from physics.