Which carbohydrate is used in the silvering of mirrors?

$A$ centigrade and a Fahrenheit thermometer are dipped in boiling water. The water temperature is lowered until the Fahrenheit thermometer registers $140^{\circ}F$. What is the fall in temperature as registered by the centigrade thermometer in $^{\circ}C$?

In which of the following are vessels and companion cells found?

$A$ compound $X$ with molecular formula $C_3H_8O$ can be oxidised to a compound $Y$ with the molecular formula $C_3H_6O_2$. $X$ is most likely to be

Which of the following metals will react with water?

$A$ pair of perpendicular lines passes through the origin and also through the points of intersection of the curve $x^2+y^2=4$ with $x+y=a$,where $a>0$. Then $a$ is equal to