A student has written the following answer to describe and explain the reactivity of group 1 metals. However, they've
made lots of mistakes. Can you correct them?
"As you go down group 1, reactivity decreases because it gets harder to gain an
Celectron lo the outer shell,
This is because as you go down group 1, the outer shell gets closer to the positive
nucleus, meaning that there is a weaker force of attraction between the nucleus
and the positive electrons on the inner shell,
There is also less electron shielding as you go down group 1, because there are
more inner shell electrons, which repel the outer shell electron,
All of these reasons mean that as you go down group 1 the outer shell electron is
harder to lose

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

i think   the answer is c hope i'm right