Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

386.

What is the solubility of a salt X at 25ºC if the saturated solution of the salt contains 0.28g in 100cm\(^3\) of the solution in mol\dm\(^3\)? 

[ X = 56.0g ]

A.

0.05

B.

0.10

C.

2.60

D.

2.80

Correct answer is A

(mass / molar mass) X (1000 / vol )

(0.28 / 56.0) X (1000 / 100 )

= 2.8 / 56 

= 0.05 mol\dm\(^3\)

387.

The properties of a good primary standard solution include the following except?

A.

High molecular mass

B.

low molecular mass

C.

high degree of purity

D.

readily available

Correct answer is B

Properties of a good standard solution

  • High purity.
  • Stability (low reactivity)
  • Low hygroscopicity (to minimize weight changes due to humidity)
  • High equivalent weight (to minimize weighing errors)
  • Non-toxicity.
  • Ready and cheap availability.
  •  High molecular mass

388.

The name of the compound CH\(_3\)C(CH\(_3\))\(_2\)CH\(_2\)CH\(_2\)CH\(_3\)

A.

2 - methyl butane

B.

2,2 - dimethyl butane

C.

2 - methyl pentane

D.

2,2 - dimethyl pentane

Correct answer is D

- The longest chain has five carbon atoms i.e PENT

- with two methyl attached to the second carbon atom 

389.

Which of the following compounds has coordinate bonds in its structure?

A.

Al\(_2\)Cl\(_6\)

B.

MgCl\(_2\)

C.

AgCl

D.

NaCl

Correct answer is A

Aluminum chloride (Al2Cl6) has coordinate dative bonding

390.

What is the percentage by mass of H in  CH3COOH

A.

1.7%

B.

5.0%

C.

6.7%

D.

7.1%

Correct answer is C

- molecular mass (or molar mass) is 60.05 g/mol

- with 4 atoms of hydrogen present

( 4 / 60 ) X 100

≈6.7%