Microcosmic salt is

• Na₄P₂O₇

• Na(NH₄)HPO₄

• Na(NH₃)HPO₄ 4H₂O

• MgNH₄PO₄

The C-O-H bond angle in ethanol is nearly

• 90°

• 104°

• 120°

• 180°

3.

A buffer solution is prepared by mixing 0.1 M ammonia and 1.0 M ammonium chloride. At 298 K, the pK_b of NH₄OH is 5.0. The pH of the buffer is

• 10.0

• 9.0

• 6.0

• 8.0

Among NH₃, HNO₃, NaN₃ and Mg₃N₂ the number of molecules having nitrogen in negative oxidation state is

• 1

• 2

• 3

• 4

Born-Haber cycle may be used to calculate

• electronegativity

• mass number

• oxidation number

• electron affinity

The heat of formation for CO₂ (g), H₂O (l) and CH₄ (g) are -400 kJ mol^-1, -280 kJ mol^-1 and -70 kJ mol^-1 respectively. The heat of combustion of CH₄ in kJ mol^-1 is

• 890

• -160

• -890

• -90

The molecule having zero dipole moment is

• CH₂Cl₂

• BF₃

• NF₃

• ClF₃

The bond angle is smallest in

• H₂O

• H₂S

• BeCl₂

• N₂O

Oxygen and sulphur both are the member of same group in periodic table but H₂O is liquid while H₂S is gas because

• molecular weight of water is more

• electronegativity of sulphur is more

• H₂S  is weak acid

• water molecules are having weak hydrogen bonds between them

Diffusion of helium gas is four times faster than

• CO₂

• SO₂

• NO₂

• O₂