Convection currents in the mantle are driven by changes in the density and the temperature of the material. select the boxes that show the correct motion of matter as its temperature and density change.

a density increases and the matter moves towards the upper mantle

b density increases and the matter moves towards the lower mantle

c density decreases and the matter moves towards the upper mantle

d density decreases and the matter moves towards the lower mantle

e temperature increases the matter moves towards the upper mantle

f temperature increases and the matter moves towards the lower mantle

g temperature decreases and the matter moves towards the upper mantle

h temperature decreases and the matter moves towards the lower mantle

The correct motion of matter as its temperature and density change,

Density increases and the matter moves towards the lower mantle

Density decreases and the matter moves towards the upper mantle

Temperature increases the matter moves towards the upper mantle

Temperature decreases and the matter moves towards the lower mantle

The correct options are B, C, E and H.  

Explanation:

Mantel is the second layer of the earth, which is situated just below the earth’s crust. Earth’s crust is the upper most layer. Mantel is quite hot, with the molten lava. There the fluid mechanics comes into action where convection currents come in action.

As the temperature rise, the density of the mantel decreases and the fluid rises to upper layer. Then it cools down and the lava again goes down. Same is with the density. As the density increases, lava does down and again comes as the density decreases in the core temperature.  

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.