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

Density of a 2.05M solution of acetic acid in water is 1.02 g/mL The molality of the solution is

Uncertainty in the position of an electron (mass = 9.1 $$\times$$ 10^-31 kg) moving with a velocity 300 ms^-1, accurate upto 0.001% will be (h = 6.63 $$\times$$ 10^-34 Js)

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