The ionic equations represent the reactions between four metals, p, q, r and s, and solutions of the salts of the same metals p + q2+ -> no reaction r + p2+ -> r2+ + p q + s2+ -> q2+ + s s + p2+ -> s2+ + p s + r2+ -> s2+ + r s + q2+ -> no reaction what is the correct order of reactivity of the metals? most > least a. p r s q b. q r s p c. q s r p d. s q p r

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.

you need to have a picture of the atom that way we can answer it

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.