n/p ratio during positron decay

• increases

• decreases

• remains constant

• All of these

What is the free energy change $∆$G when 10 moles of water at 100°C and 1 atm pressure is converted into steam at 100° C and 1 atm pressure?

• 540 cal

• -9800 cal

• 9800 cal

• 0 cal

3.

Among the following groupings which represent the collection of isoelectronic species.

• NO⁺, C${}_2^{2-}$, C${}_2^{-}$, CO

• N₂, C${}_2^{2-}$, CO, NO

• CO, NO⁺, CN^-, C${}_2^{2-}$

• NO, CN^-, N₂, O${}_2^{-}$

Which element has maximum first ionisation potential?

• Cs

• F

• Na

• He

In which of the following $∆\mathrm{E} = ∆\mathrm{H}$?

• N₂O₄ (g) $\rightleftharpoons$ 2NO₂ (g)

• 2SO₂ (g) + O₂ (g) $\rightleftharpoons$ 2SO₃ (g)

• H₂ (g) + I₂ (g) $\rightleftharpoons$ 2HI (g)

• H₂ (g) + $\frac{1}{2}$ O₂ (g) $\rightleftharpoons$H₂O (l)

The empirical formula of a compound is CH₂. One mole of this compound has a mass 42g. Its molecular formula is

• C₃H₆

• C₂H₆

• CH₂

• C₂H₂

Which of the following notations shows the product incorrectly?

• ${}_5{}^{10}\mathrm{B} (\mathrm{\alpha }, \mathrm{n}) {}_7{}^{13}\mathrm{N}$

• ${}_{96}{}^{242}\mathrm{Cm} (\mathrm{\alpha }, 2\mathrm{n}) {}_{97}{}^{243}\mathrm{Bk}$

• ${}_7{}^{14}\mathrm{N} (\mathrm{n}, \mathrm{p}) {}_6{}^{14}\mathrm{C}$

• ${}_{14}{}^{28}\mathrm{Si} (\mathrm{d}, \mathrm{y}) {}_{15}{}^{30}\mathrm{P}$

Atomic radii of which metals are same?

• Cr, Mn, Cu

• Cr, Fe, Co

• Sc, Ti, Zn

• V, N, Cr

If K_c is the equilibrium constant for the formation of NH₃, the dissociation constant of NH₃ under the same condition will be

• $\frac{1}{{\mathrm{K}}_{\mathrm{c}}}$

• ${\mathrm{K}}_{\mathrm{C}}^2$

• $\sqrt{{\mathrm{K}}_{\mathrm{C}}}$

• K_C

The pH of a soft drink is 3.92. The hydrogen ion concentration will be

( given antilog 0.08 = 1.2)

• 1.96 × 10^-2 mol L^-1

• 1.96 × 10^-3 mol L^-1

• 1.2 × 10^-4 mol L^-1

• 1.2 × 10^-3 mol L^-1