Problem 141
Match the following: List-I List-II 1\. Bell metal (i) Cu: \(60 \%-80 \%, \mathrm{Zn}: 20 \%-40 \%\) 2\. Gun metal (ii) \(\mathrm{Cu}: 75 \%-90 \%, \mathrm{Sn}: 10 \%-25 \%\) 3\. Bronze (iii) \(\mathrm{Cu}: 88 \%, \mathrm{Sn}: 10 \%, \mathrm{Zn}: 2 \%\) 4\. Brass (iv) Cu: 80\% Sn: \(20 \%\) The correct matching is: 1 2 3 4 (a) (iv) (iii) (ii) (i) (b) (iii) (iv) (ii) (i) (c) (iv) (ii) (i) (iii) (d) (iii) (iv) (i) (ii)
Problem 142
Which of the following statement is correct with reference to the ferrous and ferric ions? 1\. \(\mathrm{Fe}^{3+}\) gives brown colour with potassium ferricyanide 2\. \(\mathrm{Fe}^{2+}\) gives blue precipitate with potassium ferricyanide 3\. \(\mathrm{Fe}^{3+}\) gives red colour with potassium thiocyanate 4\. \(\mathrm{Fe}^{2+}\) gives brown colour with ammonium thiocyanate. (a) 1,4 (b) 1,2 (c) 2,3 (d) all of these
Problem 143
A colourless water soluble salt \(X\) on heating gives brown gas and leaves a metallic residue. Solution of \(X\) gives brick red precipitate with solution of \(\mathrm{K}_{2} \mathrm{CrO}_{4}\). An ammonical solution of \(X\) gives a silver mirror with formic acid. Salt \(X\) is used in making indelible election ink. Identify the salt \(X\) here? (a) \(\mathrm{AgCl}\) (b) \(\mathrm{HgNO}_{3}\) (c) \(\mathrm{AgNO}_{3}\) (d) \(\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}\)
Problem 144
Match the following: List-I List-II 1\. Nichrome (i) \(\mathrm{Pb}, \mathrm{Bi}, \mathrm{Sn}, \mathrm{Cd}\) 2\. Type metal (ii) \(\mathrm{Pb}, \mathrm{Sb}, \mathrm{Sn}\) 3\. Wood's metal (iii) \(\mathrm{Cu}, \mathrm{Al}, \mathrm{Zn}\) 4\. Devarda's alloy (iv) \(\mathrm{Fe}, \mathrm{Ni}, \mathrm{Cr}\)The correct matching is 1 2 3 (a) (ii) (i) (iii) (iv) (b) (iii) (iv) (ii) (i) (c) (iv) (ii) (i) (iii) (d) (iii) (iv) (i) (ii)
Problem 145
In the process of extraction of gold roasted gold ore \(+\mathrm{CN}^{-}+\mathrm{H}_{2} \mathrm{O} \stackrel{\mathrm{O}_{2} \rightarrow}[\mathrm{X}]+\mathrm{OH}^{-}\) \([\mathrm{X}]+\mathrm{Zn} \longrightarrow[\mathrm{Y}]+\mathrm{Au}\) \([\mathrm{X}]\) and \([\mathrm{Y}]\) are (a) \([\mathrm{X}]=\left[\mathrm{Au}(\mathrm{CN})_{2}\right]^{-},[\mathrm{Y}]=\left[\mathrm{Zn}(\mathrm{CN})_{4}\right]^{-2}\) (b) \([\mathrm{X}]=\left[\mathrm{Au}(\mathrm{CN})_{4}\right]^{-3},[\mathrm{Y}]=\left[\mathrm{Zn}(\mathrm{CN})_{4}\right]^{-2}\) (c) \([\mathrm{X}]=\left[\mathrm{Au}(\mathrm{CN})_{2}\right]^{-},[\mathrm{Y}]=\left[\mathrm{Zn}(\mathrm{CN})_{6}\right]^{-4}\) (d) \([\mathrm{X}]=\left[\mathrm{Au}(\mathrm{CN})_{4}\right]^{-},[\mathrm{Y}]=\left[\mathrm{Zn}(\mathrm{CN})_{4}\right]^{-2}\)
Problem 148
Roasting of copper pyrites is done (a) To oxidize free sulphur (b) Ro remove moisture (c) To remove volatile organic impurities (d) To decompose sulphides into oxides.
Problem 149
Which of the following statements is/are correct for electrolytic refining? (a) The electric current used is \(\mathrm{AC}\) (b) On account of electrolysis, the metal is indirectly transferred from anode to cathode (c) The impurity metal is made the anode while a thin sheet of pure metal is used as the cathode (d) The electrolyte used is a covalent compound of metal
Problem 150
vSilver is a soft metal. It is hardened by alloying it wi small amounts of (a) \(\mathrm{Cu}\) (b) \(\mathrm{Fe}\) (c) \(\mathrm{Ni}\) (d) \(\mathrm{Sn}\)
Problem 150
Silver is a soft metal. It is hardened by alloying it with small amounts of (a) \(\mathrm{Cu}\) (b) \(\overline{\mathrm{Fe}}\) (c) \(\mathrm{Ni}\) (d) \(\mathrm{Sn}\)
Problem 151
Which of the following are correctly matched? (a) Zone refining - Ultra pure Ge (b) Leaching - Extraction of \(\mathrm{Au}, \mathrm{Ag}\) (c) Cyanide process - Extraction of Au (d) Electrolyte reduction - Extraction of Al
