Which of the following metals is used in the thermite welding process? MCQ with Answer and Explanation

Explanation:
Sodium and potassium are highly reactive alkali metals that react vigorously with oxygen and moisture in the air, potentially catching fire. To prevent accidental fires, they are stored immersed in kerosene oil. Magnesium and calcium do not require such extreme storage conditions.

Explanation:
AgNO₃ + NaCl → AgCl↓ + NaNO₃ is a double displacement (precipitation) reaction where ions exchange partners. Ag⁺ pairs with Cl⁻ to form a white precipitate of AgCl, and Na⁺ remains with NO₃⁻. Option A is combination, B is single displacement, D is decomposition. Double displacement generally forms a precipitate, gas, or water. Neutralization is also a double displacement: HCl + NaOH → NaCl + H₂O.

Explanation:
Beta rays (β) consist of high-speed, high-energy electrons (β⁻) or positrons (β⁺) emitted from the nucleus during radioactive decay. In standard beta decay, a neutron converts into a proton and an electron, and the electron is ejected from the nucleus.