2. Which best describes how the scientists could explain their observations? A They thought that sediment washing in from the shore formed the ocean
floor, and continued to build out from the shore.
B They thought that strong ocean waves pushed the younger rock
material toward the middle of the ocean.
C They thought that wave erosion at the shore removed the younger rock
layers that were on top of the older rock layers.
D They thought the young rock formed at the mid-ocean ridge and pushed
the older rock toward the shore.

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.

it is b that is the answer.