A metal sphere of diameter \(7 cm\) falls through aliquid of coefficient of viscosity \(0.8 Pa.s\). When itsvelocity is \(20 cm.s^{-1}\) the viscous force acting on itis nearly ----\(N.\) (A) \(0.11\) (B) \(0.22\) (C) \(0.3\) (D) \(0.01\)
Answer
Answer: A Viscous force on the metal sphere = \(6 \pi \eta r V\) \(= 6 \times \times 0.8 \times \dfrac{3.5}{100} \times \dfrac{4}{3} \pi \left ( \dfrac{3.5}{100} \right )^{3}\times \dfrac{20}{100}N\) \(= 0.1055 \approx 0.11 N\)
A centigrade and a Fehrenhe it thermometer aredipped in boiling water. The water temperature islowered unit the Fahrenheit thermometer registers \(140^oF\). What is the fall in temperature as registered by the Centigrade thermometer (A) \(30^{\circ}\) (B) \(40^{\circ}\) (C) \(60^{\circ}\) (D) \(80^{\circ}\)
When \(CO_2\) is bubbled through a solution of barium peroxide in water: (A) carbonic acid is formed (B) \(H_2O_2\) is formed (C) \(H_2O\) is formed (D) barium hydroxide is formed
The four quantum numbers of the valence electronof potassium are: (A) \(4,0,1,+\frac{1}{2}\) (B) \(4,1,0,+\frac{1}{2}\) (C) \(4,0,0,+\frac{1}{2}\) (D) \(4,1,1,+\frac{1}{2}\)
The precipitate of \(CaF_{2}(K_{sp} =1.7\times 10^{-10})\) is obtained when equal volumes of the following are mixed (A) \(10^{-4}M Ca^{2+}+10^{-4}M F^{-}\) (B) \(10^{-2}M Ca^{2+}+10^{-3}M F^{-}\) (C) Both A and B (D) None of these