Assertion : Cytokinin are antisenescent.
Reason : Effects of cytokinins is antagonistic to ethylene.

Q. Assertion : Amount of cyanocobalamine required daily is 3 mcg
Reason : Its deficiency causes pernicious anaemia

Q. Assertion: C₄ – photosynthetic pathway is more efficient than C₃ pathway Reason: Photorespiration is suppressed in C₄ plants

Q. Assertion: $\overrightarrow{\tau }=\overrightarrow{r}\times \overrightarrow{F}but\overrightarrow{\tau }\ne \overrightarrow{F}\times \overrightarrow{r}.$
Reason: Cross product of a vector is commutative.

Q. (i)
Assertion: A circle is not a rectilinear figure.
Reason: A figure formed by straight lines only is called a rectilinear figure.
(a) Both Assertion and Reason are true and Reason is a correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not a correct explanation of Assertion.
(c) Assertion is true and Reason is false.
(d) Assertion is false and Reason is true.
(ii)
Assertion: All right angles are equal to one another.
Reason: A unique line passes through a single point.
(a) Both Assertion and Reason are true and Reason is a correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not a correct explanation of Assertion.
(c) Assertion is true and Reason is false.
(d) Assertion is false and Reason is true.

Q. Assertion : Photosensitivity of a metal is high if its work function is small.

Reason : Work function $h{f}_0$ where $f_0$ is the threshold frequency.