Which of the following is an example of interstitial hydride?

In which of the following, ortho/para substitution by an electrophile is very facile?

Copper matte contains

The symbol of an element is Une. Its atomic number is

Which one of the following is used in the hardening of leather?

The rate of attack of an electrophile is least when \(\mathrm{X}\) in the given compound is

What is the temperature at which the kinetic energy of 0.3 moles of helium is equal to the kinetic energy of 0.4 moles of argon at \(400 \mathrm{~K}\) ?

Which of the following statements about smog is/are correct? (i) Smog formed on sumny days contain oxidísing molecules. (ii) Photochemical smog contains many reactive molecules. (iii) The main polluting components of smog are oxides of carbon. (iv) The presence of carbon monoxide in air leads to the formation of ozone in smog.

The length of the common chord of the two circles \((x-a)^2+y^2=a^2\) and \(x^2+(y-b)^2=b^2\), is

A cell of emf \(10 \mathrm{~V}\) and internal resistance \(3 \Omega\) is connected in parallel with another cell of emf \(7 \mathrm{~V}\) and internal resistance \(\frac{3}{5} \Omega\), such that their positive terminals are joined together and so their are negative terminals. Their positive terminals are joined with the negative terminal and their negative terminal is joined with the positive terminal of a third cell of emf \(20 \mathrm{~V}\) with internal resistance \(2 \Omega\). The combination can be replaced by a battery of emf \(E\) and internal resistance \(r\), then the values of \(E\) and \(R\) are respectively

The effective capacitance between points \(A\) and \(B\) shown in the figure is

Let \(A=(1,2,0), B=(2,0,-1), C=(0,-2,3)\) and \(D=(-1,2,-3)\) be four points in the space. Let \(\mathrm{G}_1\) be the centroid of triangle \(A B C\) and \(G_2\) be the centroid of tetrahedron ABCD. If \(P\) divides \(G_1 G_2\) in the ratio \(4: 3\) internally then \(\mathrm{P}=\)

The length of the normal drawn at \(t=\frac{\pi}{4}\) on the curve \(x=2(\cos 2 t+t \sin 2 t), y=4(\sin 2 t+t \cos 2 t)\) is