Which one of the following sets of quantum numbers represents the highest energy level in an atom?

• n = 4, l = 0, m = 0, s = +$\frac{1}{2}$

• n = 3, l = 1, m = 1, s = +$\frac{1}{2}$

• n = 3, l = 2, m = -2, s = +$\frac{1}{2}$

• n = 3, l = 0, m = 0, s = +$\frac{1}{2}$

When O₂ is converted into O${}_2^{+}$

• both paramagnetic character and bond order increase

• bond order decreases

• paramagnetic character increases

• paramagnetic character decreases and the bond order increases

If the energies of the two photons in the ratio of 3 : 2, their wavelength will be in the ratio of

• 2 : 3

• 9 : 4

• 3 : 2

• 1 : 2

Generally, the first ionisation energy increases along a period. But there are some exceptions. The one which is not an exception is

• Be and B

• Na and Mg

• Mg and Al

• N and O

Out of the given two compounds, the vapour pressure of B at a particular temperature is

• higher than that of A

• lower than that of A

• higher or lower than A depending on the size of the vessel

• same as that of A

6.

Increasing order of carbon-carbon bond length for the following is

$\underset{\left(\mathrm{A}\right)}{{\mathrm{C}}_2{\mathrm{H}}_4} \underset{\left(\mathrm{B}\right)}{{\mathrm{C}}_2{\mathrm{H}}_2} \underset{\left(\mathrm{C}\right)}{{\mathrm{C}}_6{\mathrm{H}}_6} \underset{\left(\mathrm{D}\right)}{{\mathrm{C}}_2{\mathrm{H}}_6}$

• C < B < A < D

• B < C < A < D

• D < C < A < B

• B < A < C < D

A mixture of CaCl₂ and NaCl weighing 4.44 g is treated with sodium carbonate solution to precipitate all the calcium ions as calcium carbonate. The calcium carbonate so obtained is heated strongly to get 0.56 g of CaO. The percentage of NaCl in the mixture is (atomic mass of Ca = 40)

• 75

• 31.5

• 40.2

• 25

50 cm³ of 0.2 N HCl is titrated against 0.1 N NaOH solution. The titration was discontinued after adding 50 cm³ of NaOH. The remaining titration is completed by adding 0.5 N KOH. The volume of KOH required for completing the titration is 

• 12 cm³

• 10 cm³

• 21.0 cm³

• 16.2 cm³

The rms velocity of hydrogen is $\sqrt{7}$ times the rms velocity of nitrogen. If T is the temperature of the gas, which of the following is true?

• ${\mathrm{T}}_{{\mathrm{H}}_2} = \sqrt{7 } {\mathrm{T}}_{{\mathrm{N}}_2}$

• ${\mathrm{T}}_{{\mathrm{N}}_2} = {\mathrm{T}}_{{\mathrm{H}}_2}$

• ${\mathrm{T}}_{{\mathrm{N}}_2} = \sqrt{7} {\mathrm{T}}_{{\mathrm{H}}_2}$

• ${\mathrm{T}}_{{\mathrm{N}}_2} = 2{\mathrm{T}}_{{\mathrm{H}}_2}$

25 g of each of the following gasses are taken at 27°C and 600 mm pressure. Which of these will have the least volume?

• HCl

• HBr

• HI

• HF