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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.

661.

In the preparation of oxygen by heating KCIO3 , in the presence of MnO2 only moderate heat is needed because the catalyst acts by 2

A.

lowering the pressure of the reaction

B.

increasing the surface area of the reaction

C.

increasing the rate of the reaction

D.

increasing the energy barrier of the reaction

Correct answer is C

No explanation has been provided for this answer.

662.

Which of the following pairs of substances will react further with oxygen to form a higher oxide?

A.

CO2 and H2O

B.

NO and H2O

C.

CO and CO2

D.

SO2 and NO

Correct answer is D

No explanation has been provided for this answer.

663.

In the shown experiment (Fig. 1) the litmus paper will initially

A.

be bleached

B.

turn green

C.

turn red

D.

turn blue

Correct answer is D

NH4ClNH3+HCl. rate of diffusion of substances depends too on their molar mass, the smaller the molar mass of a substance the faster the rate of diffusion of that substance. so the litmus paper initially turns blue because ammonia will get to it first since it diffuses faster than HCl.

665.

The periodic classification is an arrangement of the elements

A.

atomic weights

B.

isotopic weights

C.

molecular weights

D.

atomic numbers

Correct answer is D

Elements in the periodic table are arranged according to their atomic number (proton number). Electronegativity increase from left to right while atomic radius increases down the group

Elements in the periodic table are arranged according to their atomic number (proton number). Electronegativity increase from left to right while atomic radius increases down the group