If 80 g of copper sulphate CuSO₄ . 5H₂O is dissolved in deionised water to make 5L of solution. The concentration of the copper sulphate solution is x $$\times$$ 10^$$-$$3 mol L^$$-$$1. The value of x is _____________.

[Atomic masses Cu : 63.54u, S : 32u, O : 16u, H : 1u]

A 50 watt bulb emits monochromatic red light of wavelength of 795 nm. The number of photons emitted per second by the bulb is x $$\times$$ 10²⁰. The value of x is __________. [Given : h = 6.63 $$\times$$ 10^$$-$$34 Js and c = 3.0 $$\times$$ 10⁸ ms^$$-$$1]

The spin-only magnetic moment value of $$B_2^ + $$ species is _____________ $$\times$$ 10^$$-$$2 BM. (Nearest integer) [Given : $$\sqrt 3 $$ = 1.73]

If the conductivity of mercury at 0$$^\circ$$C is 1.07 $$\times$$ 10⁶ S m^$$-$$1 and the resistance of a cell containing mercury is 0.243$$\Omega$$, then the cell constant of the cell is x $$\times$$ 10⁴ m^$$-$$1. The value of x is ____________. (Nearest integer)