$A$ centigrade and Fahrenheit thermometer are dipped in boiling water. The water temperature is lowered until the Fahrenheit temperature observed is $140^{\circ} F$. At that time the temperature registered by the centigrade thermometer is (in $^{\circ} C$)

Check whether the following statements are True or False:
$(a)$ The equation to convert Celsius temperature to Fahrenheit is $t^{\circ}F = \frac{5}{9}t^{\circ}C + 32$.
$(b)$ For an ideal gas,absolute zero temperature is $273.15^{\circ}C$.
$(c)$ The volume of water is maximum at $4^{\circ}C$.
$(d)$ The temperature gradient is negative if a cube block is heated at the cold end and heat transfers to the hot end.

$A$ faulty thermometer has its fixed points marked $5^{\circ}$ and $95^{\circ}$. This thermometer reads the temperature of a body as $59^{\circ}$. Then the correct temperature of the body on the Celsius scale is ........ $^{\circ}$.

In a mercury thermometer, the ice point (lower fixed point) is marked as $10^{\circ}$ and the steam point (upper fixed point) is marked as $130^{\circ}$. At $40^{\circ} C$ temperature, what will this thermometer read (in $^{\circ}$)?

What is the triple point?

What is a thermometer? What is a gas thermometer? Write its characteristics.