A wire of resistance 4 \( \Omega \) is used to make a coil of radius 7 cm. The wire has a diameter of 1.4 mm and the resistivity of its material is \( \rho = 2 \times 10^{-7} \, \Omega \, m \). The number of turns in the coil will be

Two nuclei with mass numbers A and B have density ratios of :

An unchanged capacitor is connected to a battery. How much amount of energy supplied by the battery is lost as heat while charging the capacitor ?

A hot wire voltmeter measures the voltages across the inductor, the capacitor and the resistor as 150 V, 100 V and 50 V across a series, LCR circuit. If resistance is \( 100 \, \Omega \), the current in the circuit is :

Bulb B1 is a 50 W bulb working on 100 V and Bulb B2 is a 200 W bulb also working on 100 V. The ratio of resistances of bulbs B1 to B2 is:

There is a small air bubble inside a glass sphere (\( \mu = 1.5 \)) of radius 10 cm. The bubble is 4.0 cm below the surface and is viewed normally from outside as shown. The apparent depth of the bubble will be

The S.I. unit of electron mobility is :

Which of the following is NOT correct about the Central Limit Theorem?

Identify the correct statements.
(A) A concave mirror is preferred over a plane mirror for the purpose of shaving.
(B) The absolute refractive index of a medium can be less than unity.
(C) Snell's law gives the relative refractive index of a medium.
(D) When a convex lens is placed inside a transparent medium of refractive index greater than that of its own material, it behaves as a diverging lens.
Choose the correct answer from the options given below:

Which of the following alkyl halide will undergo \(\mathrm{S}_{\mathrm{N}} 1\) reaction fastest?

The function \(f(x)=-\frac{3}{4} x^4-8 x^3-\frac{45}{2} x^2+163\) has a local maxima at

Amines are reactive in nature, mainly due to difference in electronegativity between Nitrogen and Hydrogen and, due to lone pair of electrons on Nitrogen. Amines behave like nucleophiles and as good lewis bases and there are various reactions to support this. Different degree of amines differ in their reactivity due to steric hinderance and electronic effects. Aromatic amines are less basic due to + R effect, hence have higher pk value than aliphatic amines. Basic strength of amines also depends on stability of corresponding conjugate acid in aqueous medium.
Conjugate acid of which of the following amines is most stable?

The power of the composite lens made of two thin lenses of focal lengths \(f_1\) and \(f_2\) placed in contact will be: