How many moles of magnesium phosphate, Mg₃(PO₄)² will contain 0.25 mole of oxygen atoms?

• 0.02

• 3.125 × 10^–2

• 1.25 × 10^–2

• 2.5 × 10^–2

B.

3.125 × 10^–2

According to Bohr’s theory, the angular momentum of an electron in 5th orbit is

• 25h/ π

• 1.0h/π

• 10/π

• 2.5h/π

D.

2.5h/π

Which of the following molecules/ions does not contain unpaired electrons?

• 
• 
• 
• 

A.

Uncertainty in the position of an electron (mass = 9.1 × 10^–31 kg) moving with a velocity 300 ms–1, accurate upto 0.001%, will be

• 19.2 × 10^–2 m

• 5.76 × 10^–2 m

• 1.92 × 10^–2 m

• 3.84 × 10^–2 m

C.

1.92 × 10^–2 m

Phosphorus pentachloride dissociates as follows, in a closed reaction vessel,
PCl₅ (g) ⇌ PCl₃(g) + cl₂(g)
If total pressure at equilibrium of the reaction mixture is P and degree of dissociation of PCl₅ is x, the partial pressure of PCl₃ will be

• 
• 
• 
• 

A.