JAMB Physics Past Questions & Answers - Page 117

581.

An element of nuclear number A and proton number Z emits an alpha particle from its nucleus. The nucleon number and the proton number of the new element formed are respectively

A.

(A – 2) and (Z – 2)

B.

(A + 4) and (Z + 2)

C.

(A– 4) and (Z+2)

D.

(A+ 4) and (Z – 2)

E.

(A – 4) and (Z – 2)

Correct answer is E

Let the element be S and the element formed after emission be X.

\(\implies ^{A} _{Z}S \to ^{4} _{2}He + X\)

\(\therefore X = ^{A - 4} _{Z - 2}X\).

583.

When a lever is in equilibrium, under the action of two or more forces, the algebraic sum of the moments of the forces about the point of support is

A.

anti-clockwise

B.

clockwise

C.

equal to the product to the forces

D.

numerically equal to the total forces acting

E.

equal to zero

Correct answer is E

No explanation has been provided for this answer.

585.

A gas occupies a certain volume at 27°C. At what temperature will its volume be twice times the original volume assuming that its pressure remains constant?

A.

54°C

B.

108°C

C.

150°C

D.

327°C

E.

600°C

Correct answer is D

\(\frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}}\)

Given \(V_{2} = 2V_{1}\)

\(T_{1} = 27°C + 273 = 300k\)

\(\frac{V_{1}}{300} = \frac{2V_{1}}{T_{2}}\)

\(\frac{1}{300} = \frac{2}{T_{2}} \implies T_{2} = 600k  or 327°C\)