1 This animal has a backbone, nurses its offspring: likes to gnaw, has a bushy tail: climbs trees; has reddish fur on its back and has white fur on its belly.

American red squirrel

Explanation:

The American red squirrel is the smallest squirrel. The color of the fur may vary from season to season. The color of the squirrel can also vary depending of the environment in which it lives. In summer the black stripe appears on the sides over the white fur. It has a backbone and like other mammals nurses the offsprings. It has a bushy tail. It is a native of North America. Red fur appear on the back and white on the belly. Strong claws, strong muscles, and compact body are other key features of the squirrel.

1 a

2 d

3 a

4 c

explanation:

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.