Which has the maximum number of molecules among the following?

• 44 g CO₂

• 48 g O₃

• 8 g H₂

• 8 g H₂

According to the Bohr theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon?

• n= 6 to n = 1

• n = 5 to n = 4

• n= 6 to n = 5 

• n= 6 to n = 5 

Consider the following processes Δ H (kJ/mol)

1/2 A →                               +150
3B   → 2 C + D                     -125
E + A  → 2D                        +350

For  B + D   → E + 2C, ΔH will be 

• 525 kJ/mol

• -175 kJ/mol

• -325 kJ /mol

• -325 kJ /mol

Which of the following structures is the most preferred and hence of lowest energy of SO₃ ? 

A bubble of air is underwater at temperature 15^o C  and the pressure 1.5 bar. If the bubbles rises to the surface where the temperature is 25^o C and the pressure is 1.0 bar, what will happen to the volume of the bubble?

• Volume will become greater by a factor of 1.6 

• Volume will become  greater by a factor of 1.1

• Volume will become  smaller by a factor of 0.70

• Volume will become  smaller by a factor of 0.70

What is the value of electron gain enthalpy of Na⁺ if IE₁ of Na = 5.1 eV?

• -5.1 eV

• -10.2 eV

• +2.55 eV

• +2.55 eV

Match (I) with list (II) for the  compositions of substances and select the correct answer using the code given below the lists.

• A	B	C	D
  3	4	1	2

• A	B	C	D
  2	3	4	1

• A	B	C	D
  1	2	3	5

• A	B	C	D
  1	2	3	5

8.

The half -life of a substance in a certain enzyme catalysed reaction is 138 s. The time required for the concentration of the substance to fall from 1.28 mg L^-1 is 

• 414 s

• 552 s 

• 690 s

• 690 s

Which of the following statements in incorrect?

• pure sodium metal dissolves in liquid ammonia to give blue solution

• NaOH reacts with glass to give sodium silicate

• Aluminium reacts with excess NaOH to give Al(OH)₃

• Aluminium reacts with excess NaOH to give Al(OH)₃

A 0.1  molal aqueous solution  of a weak  acid is 30%  ionised. if K_f for water is 1.86^oC/m, the freezing point of the solution will be 

• -18^oC

• -0.54^oC

• -0.36^oC

• -0.36^oC