[smr101]

I've been doing some past paper questions for my upcoming prelims, and I'm stuck on these:

1. Identify the two statements which apply to zinc.

A It displaces calcium from a solution of calcium nitrate.
B It reacts with cold water.
C It can be obtained by heating its oxide.
D It reacts with dilute hydrochloric acid.
E It is displaced from a solution of its chloride by magnesium.

2. Identify the two elements which would react together to form a
molecule with the same shape as an ammonia molecule.

Oxygen, Potassium, Phosphorous, Flourine, Lithium, Aluminium

[AWK]

Show your attempt.

[vmelkon]

For  #1, look up electrochemisty section of your book. Find the table that lists the EMF for the various half reactions and you'll know what is suppose to displace what.

For #2, what can we say about ammonia? It is not a metal alloy. The formula is NH3. The molecule is not planar thanks to Mr. Nitrogen (why is not planar?).

[Arkcon]

For number 1, can you at least exclude some options?  Does every one of them seem equally plausible?  Does one, at least, seem ridiculous?  This is important to do whenever you get a multiple choice question.  Sometimes a giant list seems daunting, and stops you from even trying -- when in fact, one option was meant to make you laugh, and relive some stress.