An atomic nucleus having low n/p ratio tries to find stability by

• the emission of an α-particle

• the emission of a positron

• capturing an orbital electron (K-electron capture)

• emission of β -particle

(₃₂Ge⁷⁶, ₃₄Se⁷⁶) and (₁₄Si³⁰, ₁₆S³²) are examples of

• isotopes and isobars

• isobars and isotones

• isotones and isotopes

• isobars and isotopes

₉₈Cf²⁴⁶ was formed along with a neutron when an unknown radioactive substance was bomabrded with ₆C¹². The unknown substance is

• ₉₁Pa²³⁴

• ₉₀Th²³⁴

• ₉₂U²³⁵

• ₉₂U²³⁸

The values of $∆\mathrm{H}$and $∆\mathrm{S}$ of a certain reaction are -400 kJ mol^-1 and -20 kJ mol^-1K^-1 respectively. The temperature below which the reaction is spontaneous, is

• 100 K

• 20°C

• 20 K

• 120°C

The enthalpy of vaporisation of a certain liquid at its boiling point of 35°C is 24.64 kJ mol^-1. The value of change in entropy for the process is

• 704 JK^-1mol^-1

• 80 JK^-1mol^-1

• 24.64 JK^-1mol^-1

• 7.04 JK^-1mol^-1

Given that,

    C + O₂ → CO₂ ; $∆$H = -x kJ

2CO + O₂ → 2CO₂ ;$∆$H = -y kJ

The heat of formation of carbon monoxide will be

• $\frac{\mathrm{y} - 2\mathrm{x}}{2}$

• y + 2x

• 2x - y

• $\frac{2\mathrm{x} - \mathrm{y}}{2}$

In case of heteronuclear diatomics of the type AB, where A is more electronegative than B, bonding molecular orbital resembles the character of A more than that of B. The statement 

• is false

• is true

• cannot be evaluated since data is not sufficient

• is true only for certain systems

The value of $∆$H for cooling 2 mole of an ideal monoatomic gas from 225°C to 125°C at constant pressure will be [given C_p = $\frac{5}{2}\mathrm{R}$].

• 250 R

• -500 R

• 500 R

• -250 R

19.

The pH of 10^-4M KOH solution will be

• 4

• 11

• 10.5

• 10

The system that contains the maximum number of atoms is

• 4.25 g of NH₃

• 8 g of O₂

• 2 g of H₂

• 4 g of He