Which gas is primarily responsible for the greenhouse effect from burning fossil fuels? 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:
Across period 3, ionization energy increases from Na to Ar. Chlorine has high ionization energy due to high effective nuclear charge and small atomic radius, though Argon is highest. Among these, Cl has highest IE.

Explanation:
The modern periodic law, established by Henry Moseley, states that the properties of elements are periodic functions of their atomic numbers. Mendeleev’s original table was based on atomic mass, but the modern version uses atomic number which resolves anomalies like Ar (Z=18, mass 40) and K (Z=19, mass 39).