Chemistry Past Questions

3771

A solution X, on mixing with AgNO$$_3$$ solution gives a white precipitate soluble in aqueous NH$$_3$$, a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

• A. Al$$^{3+}$$, Cl$$^-$$
• B. Hg$$^+$$, SO$$_4 ^{2-}$$
• C. Pb$$^{2+}$$, Cl$$^-$$
• D. Ag$$^+$$, SO$$_4 ^{2-}$$
3772

How many electrons will be found in the nucleus of an atom with mass number 23 and 17 neutrons?

• A. none
• B. 6
• C. 7
• D. 8
3773

An element Z contains 80% of $$^{16} _8$$Z and 20% of $$^{18} _8$$Z. Its relative atomic mass is

• A. 16.2
• B. 17.6
• C. 16.0
• D. 16.4
3774

When the end alkyl groups of ethyl ethanoate are interchanged, the compound formed is

• A. propylmethanoate
• B. ethylpropanoate
• C. methyl ethanoate
• D. methyl propanoate
3775

The part of the total energy of a system that accounts for the useful work done in a system is known as

• A. Enthalpy change
• B. None of the above
• C. Gibb's free energy
• D. Entropy