Which of the following is a fossil fuel? MCQ with Answer and Explanation

Explanation:
Turmeric contains curcumin, a natural indicator that is yellow in acidic/neutral and turns reddish-brown in basic medium. Soap solution is basic (pH ~9-10), thus the stain changes color. This is used as a test for basicity. Vinegar or lemon juice (acid) can reverse the color. Soap is alkaline due to hydrolysis.

Explanation:
KCl (potassium chloride) is an ionic (electrovalent) compound formed by transfer of one electron from K to Cl, giving K⁺ and Cl⁻ ions held by electrostatic attraction. CH₄, CCl₄, CO₂ are covalent compounds with electron sharing. Electrovalent compounds have high melting points, conduct electricity in molten/aqueous state, and are generally soluble in water.

Explanation:
Calgon is the trade name for sodium hexametaphosphate (Na6P6O18). It is used to soften hard water because the hexametaphosphate ion binds (chelates) with calcium and magnesium ions in the water, forming a soluble complex. This prevents the metal ions from interfering with soap lathering.