X ' is a protecting colloid. The following data is obtained for preventing the coagulation of 10 mL of gold sol to which 1 mL of \(10 \% \mathrm{NaCl}\) is added. What is the gold number of ' \(X\) '?

Which one of the following reactions is not feasible ?

Consider the following reactions :


\(Y\) can be conserted to \(X\) on heating with at temperature :

The wavelength associated with the electron moving in the first orbit of hydrogen atom with velocity \(2.2 \times 10^6 \mathrm{~ms}^{-1}\) (in nm) is
\(\left(m_e=9.0 \times 10^{-31} \mathrm{~kg}, h=6.6 \times 10^{-34} \mathrm{Js}\right)\)

\(A, B, C\) and \(D\) are four different gases with critical temperatures \(304.1,154.3,405.5\) and \(126.0 \mathrm{~K}\) respectively. While cooling the gas, which gets liquefied first?

The structure of the nitrogen containing heterocyclic base given below represents

In \(\mathrm{A}_{\mathrm{x}} \mathrm{B}_{\mathrm{y}}\) crystal structure, \(\mathrm{A}\) atoms occupied all octahedral as well as all tetrahedral voids and B atoms are at FCC centres. What is the formula of compound \(\mathrm{A}_{\mathrm{x}} \mathrm{B}_{\mathrm{y}}\).

Consider the following:
Assertion (A) : Dipole moment of \(\mathrm{NF}_3\) is lesser than \(\mathrm{NH}_3\)
Reason (R) : In NF \({ }_3\), the orbital dipole due to lone pair of electrons is in the opposite direction to the resultant dipole moment of the three N-F bonds
The correct answer is

A vector perpendicular to the vector \((4 \hat{\mathrm{i}}-3 \hat{\mathrm{j}})\) is

Two towers \(A\) and \(B\), each of height \(20 \mathrm{~m}\) are situated a distance \(200 \mathrm{~m}\) apart. A body thrown horizontally from the top of the tower \(A\) with a velocity \(20 \mathrm{~ms}^{-1}\) towards the tower \(B\) hits the ground at point \(P\) and another body thrown horizontally from the top of tower \(B\) with a velocity \(30 \mathrm{~ms}^{-1}\) towards the tower \(A\) hits the ground at point \(Q\). If a car starting from rest from \(P\) reaches \(Q\) in 10 seconds, then the acceleration of the car is \(\left(\right.\) acceleration due to gravity \(\left.=10 \mathrm{~ms}^{-2}\right)\)

A body projected from the ground reaches a point \(X\) in its path after 3 seconds and from there it reaches the ground after further 6 seconds. The vertical distance of the point \(X\) from the ground is (acceleration due to gravity \(=10 \mathrm{~ms}^{-2}\) )

Which of the following alloys are correctly matched with their uses?
(i) \(\mathrm{Li} / \mathrm{Mg}\) armour plates
(ii) \(\mathrm{Cu} / \mathrm{Be}\) high strength springs
(iii) \(\mathrm{Mg} / \mathrm{Al}\) aircraft construction

The area (in sq. units) of the region lying in the first quadrant and enclosed by the $X$-axis, the straight line $x-\sqrt{3}y=0$ and the circle $x^2+y^2=4$ is