JAMB Past Questions and Answers - Page 1246

6,226.

The products of the thermal decomposition of ammonium trioxonitrate(v) are?

A.

Nitrogen (I) Oxide and Water

B.

Ammonia and Oxide

C.

Nitrogen and Water

D.

Nitrogen (IV) Oxide and Water

Correct answer is A

NH\(_4\)NO\(_3\) Ammonium Trioxonitrate(V) , unlike all other metallic trioxonitrates(v), decomposes on heating to give nitrogen(i)oxide N\(_2\)O and water.

6,227.

Four elements P, Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively. Which of these elements is noble gas? 

A.

P

B.

Q

C.

R

D.

S

Correct answer is B

They are the most stable due to having the maximum number of valence electrons their outer shell can hold. Therefore, they rarely react with other elements since they are already stable.

6,228.

The cost incurred by departments that support the production departments with such activities as maintenance, production control and storage are called?

A.

Autonomous costs

B.

Service costs

C.

Supporting cost

D.

Subsidiary costs

Correct answer is B

Service costs are the costs incurred to provide or deliver a service. They have the element of manufacturing cost but are not directly involved in production. They include cost such as the use of power and water; fee for use of furniture carpeting/curtains, costs such as cleaning of common areas, costs of concierge or maintenance of common garden.

6,229.

If the quantity of oxygen occupying 2.76L container at a pressure of 0.825 atm and 300k is reduced by one-half, what is the pressure exerted by the remaining gas?

A.

1.650atm

B.

0.825atm

C.

0.413atm

D.

0.275atm

Correct answer is A

Using the combined gas law formula,

Given that P\(_1\) = 0.825,   V\(_1\) = 2.76 L, V\(_2\) = 1.38 L, P\(_2\) = ?

And T1 = T2; we would have P\(_2\) = [ P\(_1\) X V\(_1\) ] ÷ V\(_2\)

: [0.825 X 2.76]  ÷ 1.38

= 1.650atm

6,230.

When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?

A.

Oxyethene

B.

Oxyhydrocarbon flame

C.

Oxyacetylene flame

D.

Oxymethane flame

Correct answer is C

The reaction of calcium carbide with water, producing acetylene and calcium hydroxide, was discovered by Friedrich Wöhler in 1862. This reaction was the basis of the industrial manufacture of acetylene, and is the major industrial use of calcium carbide.