Which plastic is used for making non-stick cookware? MCQ with Answer and Explanation

Explanation:
Nickel (finely divided) catalyzes the addition of hydrogen to unsaturated vegetable oils to form solid vanaspati ghee. It provides surface for reaction. Platinum and palladium also work but are expensive. Iron is used in Haber process. V₂O₅ in Contact process.

Explanation:
Azotobacter is a free-living aerobic bacterium that fixes atmospheric nitrogen in the soil, making it available to non-leguminous crops. Rhizobium is symbiotic and specific to legumes. Nitrobacter and Nitrosomonas are involved in nitrification (converting ammonia to nitrites/nitrates), not nitrogen fixation.

Explanation:
In AlCl₃, aluminium combines with three chlorine atoms. Chlorine has a valency of 1 (needs one electron to complete its octet). By the criss-cross method, Al has valency 3 because it loses three electrons to achieve a stable octet (Al³⁺). Thus, the formula is AlCl₃. Aluminium's electronic configuration is 2,8,3, so it loses three valence electrons. Exam tip: Valency equals the number of electrons lost, gained, or shared to complete octet.