Two cells of emf 10 V and 6 V, each having internal resistances of \(2 \Omega\) are connected in parallel across points A and B. The equivalent emf of the cells is

Match List-I with List-II:

List-I	List-II
(A) Current	(I) Opposition to flow of current
(B) Resistance	(II) Rate of flow of charge
(C) Resistivity	(III) Work done per unit charge
(D) EMF	(IV) Resistance per unit length \( \times \) unit cross sectional area

Choose the correct answer from the options given below:

A piece of silver and another of silicon are cooled from 15 ℃ to 3 ℃. What will be the effect on resistance of each?

A cube of side \( a \) has a charge \( Q \) at each of its vertices. What is the potential due to this charge array at the centre of the cube?

The half life of a radioactive substance is 30 s. Calculate the time taken for the sample to decay to \( \frac{3}{4} \) th its initial value.

Which of the following statement(s) is/are true for p-type semiconductors?
(A) Holes are minority carriers and pentavalent atoms are the dopants.
(B) Electrons are majority carriers and trivalent atoms are the dopants.
(C) Holes are majority carriers and trivalent atoms are the dopants.
(D) Electrons are minority carriers and trivalent atoms are the dopants.
Choose the correct answer from the options given below:

Given below are two statements:
Statement I : There is a need to translate the original low frequency base band signal into high radio frequency before transmission
Statement II : To transmit a signal an antenna is required. As frequency increases size of antenna decreases.
In the light of the above statements, choose the most appropriate answer from the options given below.

Which one of the following regions is not present in transcriptional unit of DNA

Choose the correct products formed in acidic medium.
\(5 \mathrm{SO}_3^{2-}+2 \mathrm{MnO}_4^{-}+6 \mathrm{H}^{+} \rightarrow ?\)

Answer the question on basis of passage given below :
Vitamins represent a group of organic compounds which are needed in small amount for the healthy growth and maintenance of our body. These are not synthesized by the body and are supplied in the diet. The deficiency of vitamins can be supplemented with medicines. Which vitamins are water soluble ?

p-block elements are placed in groups 13 to 18 of the periodic table. Group 15 is nitrogen family. Nitrogen makes various compounds like \(NH _3, HNO _3, N_2 O , NO _2\) etc. Phosphorus exists in the form of white and red phosphorus. White phosphorus glows in dark. \(PH _3\) gas is used as smoke screen. Group 16 is called oxygen family. Dry air contains \(21\% O_2\) gas by volume. Combined sulphur exists as sulphates such as gypsum, epsome salt, baryte etc. The allotropic forms of sulphur are Rhombic and monoclinic sulphur. \(S_2\) is paramagnetic like \(O_2\) and it stable at high temperature. Group 17 is Halogen family. \(F_2\) is highly reactive, \(C l_2\) is greenish yellow gas. Both \(S O_2\) and \(C l_2\) are used for bleaching. Group 18 is Noble gas family but some noble gases also form compounds.
Complete hydrolysis of \(XeF _6\) gives HF and \(XeO _3\) as main products.
The product of complete hydrolysis of \(XeF _6\) in the following reaction is
\(XeF _6+ H _2 O \rightarrow ?+ HF\)

Which organism was used by T.H. Morgan for his experiments ?

Aniline upon heating with concentrated \(HNO_3\) and concentrated \(H_2SO_4\) mixture gives: