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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.

191.

The dehydration of CH3CH2CH2CH2OH will give?

A.

HC≡CCH2CH3

B.

CH2≡CH2CH3

C.

CH3C≡CCH3

D.

CH3CH=CHCH3

Correct answer is D

An alkene is produced when dehydration of alcohol is performed. Alcohol dehydration is an example of an elimination reaction which is quite the opposite of substitution reaction and addition reaction.

The products of the dehydration of a primary alkanol are water and an alk-1-ene (1-alkene).

Butanol gives a mixture of but-1-ene and but-2-ene when dehydrated.

192.

The pollutant usually presents in a city which generates its electricity from coal?

A.

fog

B.

carbon(ii)oxide

C.

smog

D.

sulphur(iv)oxide

Correct answer is D

In the majority of power plants, sulfur appears due to coal burning which is used to generate electricity.

193.

The reactions below represent neutralization reaction, in which of them is the value of ΔH highest?

A.

CH3CH2COOH + KOH → CH3CH2COOK + H2O

B.

NH4OH + HCL → NH4 + H2O

C.

NaOH + HCL → NaCL + H2O

D.

CH3COOH + NaOH → CH3COONa + H2O

Correct answer is C

The enthalpy change of neutralisation involving weak acids are smaller in magnitude compared to that between strong acids and strong bases. This is because weak acids/bases are partially dissociated, which means not all hydrogen ions are free to react with hydroxide ions.

 For strong acids and bases, the enthalpy of neutralisation values are always closely similar with the values -57 and -58 KJ/mol. We know that strong acids completely ionize in water. In case of weak acids, only partial dissociation of its ions occurs.

194.

If the volume of a given mass of a gas at 0ºc is 29.5cm3. What will be the volume of the gas at 15ºc, given that the pressure remains constant. 

A.

31.6

B.

62.2

C.

32.7

D.

31.1

Correct answer is D

Charles' law is a special case of the ideal gas law in which the pressure of a gas is constant.

Charles's law defines the direct relationship between temperature and volume.

GIVEN DATA: V1 = 29.5cm3,  V2 = ? ,  T1 = 0ºc or 273k,  T2 = 15ºc or 288k

V1T1V2T2

V2 = V1xT2T1 → 29.5x288273

V2 = 31.1cm3

195.

In which of the following will hydrogen form ionic compound? 

A.

HCL

B.

NaH

C.

NH3

D.

CH4

Correct answer is B

NaH is a saline (salt-like) hydride, composed of Na+ and H− ions