4. air is made up of gas particles. these particles exert pressure on every object they collide against. this pressure is known as air pressure. which of the following statements about air pressure is true? air pressure decreases as altitude increases the atmosphere's air pressure does not vary warm air tends to have a higher air pressure than cold air air pressure increases as altitude increases

Air Pressure decreases as altitude increases.

Explanation: The pressure in the atmosphere at any level can be termed as the total weight of the air at level.

The pressure at lower levels is higher than the pressure at elevated distances because the air molecules are stick to the surface of the earth due to the gravitational pull.

Thus at higher altitudes, due to decrease of the atmospheric air, pressure also decreases.

- lead + phosphoric acid = hydrogen + lead(ii) phosphate

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.