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.

2,266.

The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If the molar mass of X is 36 g, the number of moles of X dissolved at 343 K is

A.

0.2 moles

B.

0.7 moles

C.

1.5 moles

D.

2.0 moles

E.

3.0 moles

Correct answer is D

The molar mass of x = 36g. At 343k, 72g of x dissolved 

Molarity of x = \(\frac{72}{36}\) = 2.00moles.

2,267.

The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If 80 g each of X and Y are taken up in 100 g of water at 353 K we shall have

A.

only 10g of X undissolved

B.

only 16 g of Y undissolved

C.

10 g of X and 16 g of Y undissolved

D.

all X and Y dissolved

E.

all X and Y undissolved

Correct answer is B

For salt X, from the graph, 80g of X dissolves by 349K, so by 353K, all 80g of X is dissolved totally in 100g of water. For salt Y, from the graph, 64g of Y dissolves by 353K, so (80-64)g of Y is left undissolved. This is 16g of Y left undissolved at that temperature.

2,268.

The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. At room temperature (300 K)

A.

Y is twice as soluble as X

B.

X is twice as soluble as Y

C.

X and Y are soluble to the same extent

D.

X is three times as soluble as Y

E.

Y is three times as soluble as X

Correct answer is A

No explanation has been provided for this answer.

2,269.

Figure 1 above shows part of the periodic Table which of the elements belongs to the p-block?

A.

S, T and U

B.

V, W and X

C.

S and T only

D.

P, Q and R

E.

V, W, X and S

Correct answer is D

No explanation has been provided for this answer.

2,270.

The I.U.P.A.C name for the compound is

A.

isopropylethene

B.

acetylene

C.

3- methylbutane

D.

2-methylbutane

E.

5-methylpentane

Correct answer is D

No explanation has been provided for this answer.