₁₁Na²⁴ 1s radioactive and it decays to:

• ₉F²⁰ and $\mathrm{\alpha }$-particles

• ₁₃Al²⁴ and positron

• ₁₁Na²³ and neutron

• ₁₂Mg²⁴ and $\mathrm{\beta }$-particles

A 100 mL 0.1 = (M) solution of ammonium acetate is diluted by adding 100 mL of water. The pH of the resulting solution will be (pK_a of acetic acid is nearly equal to pK_b of NH₄OH).

• 4.9

• 5.0

• 7.0

• 10.0

Equal weights of CH₃ and H₂ are mixed in an empty container at 25°C. the fraction of the total pressure exerted by H₂ is:

• 1/9

• 1/2

• 8/9

• 16/17

In a reversible chemical reaction at equilibrium, if the concentration of any one of the reactants is doubled, then the equilibrium constant will:

• also be doubled

• be halved

• remains the same

• becomes one-fourth

Which of the following does not represent the mathematical expression for the Heisenberg uncertainty principle?

• $∆$x ^.$∆$p $⩾$ h/(4$\mathrm{\pi }$)

• $∆$x ^. $∆v$ $⩾$ h/(4$\mathrm{\pi m}$)

• $∆E$ ^. $∆t$ $⩾$ h/(4$\mathrm{\pi }$)

• $∆E$ ^. $∆x$ $⩾$ h/(4$\mathrm{\pi }$)

The equivalent weight of K₂Cr₂O₇ in acidic medium is expressed in terms of its molecular weight (M) as:

• M/3

• M/4

• M/6

• M/7

Which of the following is correct?

• Radius of Ca²⁺ < Cl^- < S^2-

• Radius of Cl^- < S^2- < Ca²⁺

• Radius of Cl^- = S^2- = Ca²⁺

• Radius of S^2- < Cl^- < Ca²⁺

The state of hybridization of the central atom and the number of lone pairs over the central atom in POCl₃
are:

• sp , 0

• sp² , 0

• sp³ , 0

• dsp² , 1

20 mL 0.1 (N) acetic acid is mixed with 10 ml  0.l(N) solution of NaOH. The pH of the resulting solution is (pK_b of acetic acid is 4.74)

• 3.74

• 4.74

• 5.74

• 6.74

Which of the following is correct?

• Evaporation of water causes an increase in disorder of the system

• Melting of ice causes a decrease in the randomness of the system

• Condensation of steam causes an increase in disorder of the system

• There is practically no change in the randomness of the system when water is evaporated