Consider the following reactions:
$3NiS + 2HNO_3 + 6HCl \rightarrow 3NiCl_2 + 2NO + 3S + 4H_2O$
$NiCl_2 + 2NH_4OH + 2(CH_3C(=NOH)C(=NOH)CH_3) \rightarrow B + 2NH_4Cl + 4H_2O$
The number of protons that do not involve in hydrogen bonding in the product $B$ is:

$A$ block of mass $2 \ kg$ is tied to one end of a $2 \ m$ long metal wire of $1.0 \ mm^2$ area of cross-section and rotated in a vertical circle such that the tension in the wire is zero at the highest point. If the maximum elongation in the wire is $2 \ mm$, the Young's modulus of the metal is (Acceleration due to gravity $= 10 \ ms^{-2}$)

Explain why $BeH_{2}$ molecule has a zero dipole moment although the $Be-H$ bonds are polar.

An unbiased coin is tossed to get $2$ points for turning up a head and $1$ point for the tail. If three unbiased coins are tossed simultaneously,then the probability of getting a total of an odd number of points is

Two identical piano wires have a fundamental frequency of $600 \text{ Hz}$ when kept under the same tension. What fractional increase in the tension of one wire will lead to the occurrence of $6 \text{ beats per second}$ when both wires vibrate simultaneously?

Which of the following reactions will yield $2-$propanol? Select the correct answer from $a, b, c$ and $d$.
$(I)$ $CH_2=CH-CH_3 + H_2O \xrightarrow{H^+} $
$(II)$ $CH_3CHO \xrightarrow[(ii) H_2O]{(i) CH_3MgI}$
$(III)$ $CH_2O \xrightarrow[(ii) H_2O]{(i) C_2H_5MgI}$
$(IV)$ $CH_2=CH-CH_3 \xrightarrow{\text{neutral } KMnO_4}$