What is the force between two small charged spheres having charges of \( 4 \times 10^{-7} \text{ C} \) and \( 6 \times 10^{-7} \text{ C} \) placed 60 cm apart in air ?

Match List-I with List-II :

List - I	List - II
(A) Electric potential due to point charge	(I) \( \propto \frac{1}{r^2} \)
(B) Electric potential due to a dipole on axial line	(II) \( \propto \frac{1}{r^3} \)
(C) Electric field intensity due to a dipole on axial line	(III) \( \propto \frac{1}{r} \)
(D) Electric field intensity due to a quadrapole	(IV) \( \propto \frac{1}{r^4} \)

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The least distance of distinct vision of a person is 50 cm. He wants to read a book placed at 25 cm. The focal length of the spectacles would be :

A capacitor charged from a 50 V d.c. supply is found to have a charge of \( 10 \ \mu\text{C} \).The capacitance of the capacitor would be:

A radioactive nucleus M undergoes series of decays given below: M \(\xrightarrow{\beta^- decay}\) N \(\xrightarrow{\gamma decay}\) O \(\xrightarrow{\alpha decay}\) P. The mass number of M is 150 and Atomic No of M is 64. The Atomic number of P is

During transmission of electrical energy by transformer, near the consumer

A radioactive source (Phosphorus-32) has an initial activity 10 \(\mu\)Ci, its half life is 14 days. What time elapses before the activity falls to 1.25 \(\mu\)Ci ?

What is the coordination number of Fe in \(\left[ Fe ( CO )_5\right]\) and \(\left[ Fe \left( C _2 O _4\right)_3\right]^{3-}\) respectively?

Choose the correct relation between focal length f and radius of curvature R of a convex mirror from the following:

In a diffraction pattern due to a narrow slit of width a, alternate dark and bright fringe pattern is obtained on a screen kept at distance D from the slit. Choose the correct option.
(A) The angular width of central maximum is given by 2D/a, linear width is given by 2D\lambda/a
(B) When the size of aperture, a is quite large, the diffraction effect is negligible,
(C) For light of smaller wavelength, angular width of central maximum increases, while linear width decreases,
(D) Angular width of central maximum does not decrease while linear width decreases on decreasing distance of screen from slit.
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Which one of these tripositive ions is the most stable in aqueous solution?

Let \(A=\{a, b, c\}\). Then number of relations containing \((a, b)\) and \((b, c)\) which are reflexive and transitive but not symmetric is :

Observe the figures and answer the question.

The correct sequence for parts labelled (i), (ii), (iii) and (iv) in the figure is:
A. Plumule
B. Suspensor
C. Cotyledons
D. Radicle
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