The correct increasing order of the acid strength of benzoic acid (I), 4-nitrobenzoic acid (II), 3,4-dinitrobenzoic acid (III) and 4-methoxybenzoic acid (IV) is

• I < II < III < IV

• II < I < IV < III

• IV < I < II < III

• IV < II < I < III

Choose the correct order of decreasing basic strength of the following compounds in aqueous solution

(i) C₆H₅NH₂

(ii) C₂H₅NH₂

(iii) NH₃

(iv) (CH₃)₂NH

• (i) > (ii) > (iii) > (iv)

• (iv) > (ii) > (iii) > (i)

• (ii) > (i) > (iii) > (iv)

• (iv) > (iii) > (ii) > (i)

The shortest wavelength of the line in hydrogen atomic spectrum of Lyman series when R_H = 109678 cm^-1 is

• 1002.7 Å

• 1215.67 Å

• 1127.30 Å

• 911.7 Å

Arrange the following species in the correct order of their stability

C₂, Li₂, O${}_2^{+}$, He${}_2^{+}$

• Li₂ < He${}_2^{+}$ < O${}_2^{+}$ < C₂

• C₂ < O${}_2^{+}$ < Li₂ < He${}_2^{+}$

• He${}_2^{+}$ < Li₂ < C₂ < O${}_2^{+}$

• O${}_2^{+}$ < C₂ < Li₂ < He${}_2^{+}$

Molecular formulae and shapes of some molecules are given below. Choose the incorrect match.

• NH₃ - Trigonal pyramidal

• SF₄ - Tetrahedral

• ClF₃ - T-shaped

• PCl₅ - Triginal bipyramidal

If two moles of an ideal gas at 500 K occupies a volume of 41 L, the pressure of the gas is (R = 0.082 L atm K^-1 mol^-1)

• 2 atm

• 3 atm

• 4 atm

• 5 atm

At 273 K, the density of a certain gaseous oxide at 2 atm is same as that of dioxygen at 5 atm. The molecular mass of the oxide (in g mol^-1) is

• 80

• 64

• 32

• 160

Which of the following are isoelectronic species?

(i) NH₃

(ii) CH${}_3^{+}$

(iii) NH${}_2^{-}$

(iv) NH${}_4^{+}$

Choose the correct answer from the codes given below.

• (i), (ii), (iii)

• (ii), (iii), (iv)

• (i), (ii), (iv)

• (i), (iii), (iv)

The salt of an alkali metal gives violet colour in the flame test. Its aqueous solution gives a white precipitate with barium chloride in hydrochloric acid medium. The salt is

• K₂SO₄

• KCl

• Na₂SO₄

• K₂CO₃

In which one of the following the central atom is sp³ hydridised?

• NH${}_4^{+}$

• BF₃

• SF₆

• PCl₅