Due to the more rigid nature of their covalent bonds, nonmetals show low and high brittleness.

The right answer is ductility.

A non-metal is a chemical element whose single-body atoms are joined by covalent bonds or intermolecular bonds, and not by metal bonds.

In their solid state, the nonmetals have dull or weakly shiny surfaces (although those of iodine have metallic reflections), are rather fragile and brittle (with the notable exception of diamond carbon), and are devoid of the elasticity, malleability and ductility characteristic of metals.

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 terrae but not 100 percent sure. ▓▬▬ §