Washing soda (Na₂CO₃·10H₂O) is obtained by: MCQ with Answer and Explanation

Explanation:
Salt is soluble in water, sand is not. Add water, stir to dissolve salt, filter to separate sand. Then evaporate the filtrate to recover salt. Sublimation separates sublimable solids (NH₄Cl, naphthalene). Magnetic for magnetic materials. Fractional distillation for liquid mixtures. This is a standard separation technique.

Explanation:
Isotopes are atoms of the same element (same atomic number, same number of protons) but different mass numbers due to varying number of neutrons. For example, ¹²C, ¹³C, ¹⁴C. Their chemical properties are similar but physical properties (mass, density, rate of diffusion) differ. Isobars have same mass number but different atomic numbers.

Explanation:
The diagonal relationship occurs when elements in the second period resemble elements in the third period of the next group due to similar ionic sizes and charge-to-radius ratios (polarizing power). Li-Mg, Be-Al, and B-Si are all classic examples of this phenomenon.