Choose all of the chemical reactions which correctly show that chemical reactions must obey the law of conservation of matter. ch4 + 2o2 → co2 + h2o h2 + o2 → h2o c6h12o6 + 6o2 → 6co2 + 6h2o 2co + o2 → 2co2 4p + o2 p4o10

CH4 + 2O2 → CO2 + H2O

C6H12O6 + 6O2 → 6CO2 + 6H2O

2CO + O2 → 2CO2

Explanation: I just got the answer from Usa test prep this is it but if it is not for Usa test prep than go with the other answer

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.