The synthesis of crotonaldehyde from acetaldehyde is an example of $.......$ reaction.

Mass $M$ is divided into two parts $xM$ and $(1-x)M$. For a given separation,the value of $x$ for which the gravitational attraction between the two pieces becomes maximum is

The half-life of a radioactive substance against $\alpha$-decay is $1.2 \times 10^7 \, s$. What is the decay rate for $4.0 \times 10^{15}$ atoms of the substance?

Assertion : Comparative biochemistry provides a strong evidence in favour of common ancestry of living beings.
Reason : Genetic code is universal.

The set of solutions of the system of equations
$
\begin{aligned}
x+y & =\frac{2 \pi}{3} \\
\text{and} \quad \cos x+\cos y & =\frac{3}{2},
\end{aligned}
$
where $x, y$ are real,is

Give the correct order of electrical conductivity of aqueous solution of the following complexes:
$A. [Pt(NH_3)_6]Cl_4$
$B. [Cr(NH_3)_6]Cl_3$
$C. [Co(NH_3)_4Cl_2]Cl$
$D. K_2[PtCl_6]$