$A$ three-digit number $n$ is such that the last two digits are equal and differ from the first digit. The number of such $n$'s is:

Assign $A, B, C, D$ from the given type of reaction.
$NaCl + AgNO_3 \longrightarrow AgCl \downarrow + NaNO_3$

The Test-tube Baby Programme employs which one of the following techniques?

At $298 \ K$,the value of $-\frac{\Delta[Br^-]}{\Delta t}$ for the reaction $5 Br^- (aq) + BrO_3^- (aq) + 6 H^+ (aq) \rightarrow 3 Br_2 (aq) + 3 H_2 O (l)$ is $x \ mol \ L^{-1} \ min^{-1}$. What is the rate (in $mol \ L^{-1} \ min^{-1}$) of this reaction?

If $\operatorname{adj}\begin{bmatrix} 1 & 0 & 2 \\ -1 & 1 & -2 \\ 0 & 2 & 1 \end{bmatrix} = \begin{bmatrix} 5 & a & -2 \\ 1 & 1 & 0 \\ -2 & -2 & b \end{bmatrix}$,then $\begin{bmatrix} a & b \end{bmatrix}$ is equal to

The function $f(x) = \frac{x}{2} + \frac{2}{x}$ has a local minimum at $x = $ ..........