JAMB Chemistry Past Questions & Answers - Page 30

146.

The inherited traits of an organism are controlled by?

A.

RNA molecules

B.

Nucleotides

C.

DNA molecules

D.

Enzymes

Correct answer is C

DNA now has three distinct functions—genetics, immunological, and structural—that are widely disparate and variously dependent on the sugar phosphate backbone and the bases.

147.

220g of carbon dioxide contains ----- moles

A.

5

B.

6

C.

3

D.

4

Correct answer is A

One mole of carbon dioxide molecules has a mass of 44.01 g

: 5  mole of carbon dioxide molecules has a mass of 220g

148.

The mass of one Avogadro number of helium atoms is?

A.

1.00gram

B.

4.00gram

C.

8.00gram

D.

6.00gram

Correct answer is B

Avogadro's number is an absolute number: there are 6.022×10\(^23\) elementary entities in 1 mole.

 helium has a molar mass of 4.0 grams per mole. So one mole of helium has a mass of 4.0 grams.

149.

The mass number of a nucleus is?

A.

Always less than its atomic number

B.

The sum of the number of protons and neutrons present in the nucleus

C.

Always more than the atomic weight

D.

A fraction

Correct answer is B

mass number, is the sum of the numbers of protons and neutrons present in the nucleus of an atom.

150.

The reactivity of fluorine is due to?

A.

its high electro negativity

B.

small size of fluorine atom

C.

availability of D-orbitals

D.

strong f-f bond

Correct answer is A

fluorine (F), most reactive chemical element and the lightest member of the halogen elements.

 As the most electronegative element, it is extremely reactive.