The freezing point of oxygen is $-{217}^{\mathrm{o}}\mathrm{C}$ and hydrogen is nearly $-{259}^{\mathrm{o}}\mathrm{C}$. A lab is lowering the temperature inside a fridge. Which will freeze first? How much colder does it have to be for both to freeze?

An elevator descends into a mine shaft at the rate of $6$ metre per minute. If the descendent starts from the ground level, how long will it take to reach $240$ metres?

The temperature at $1:00 \mathrm{p}.\mathrm{m}.$ was ${10}^{\mathrm{o}}\mathrm{C}$ above zero. If it decreases at the rate of $2^{\mathrm{o}}\mathrm{C}$ per hour until $10 \mathrm{p}.\mathrm{m}.$, at what time would the temperature be $6^{\mathrm{o}}\mathrm{C}$ below zero?

Write True or False.

Sum of two negative integers is a positive integer.

Rohit earns profit of $₹1$ by selling one pen and suffers a loss of $50$ paise by selling one pencil. One day Rohit earns $₹5$. If he sold $25$ pens, how many pencils did he sell?