<em><u>examples of metalloids :
</u>Boron,Silicon ,Germanium are some metalloids ...
<u>what they do:
</u>they are used to form the semiconductors and these semiconductors are used in modern computer technology like in circuits ,chips and computer based gadgets... :) <u>
</u></em>
Answer:
The volume of hydrogen gas produced at STP is 4.90 liters.
Explanation:

Moles of aluminium =
According to reaction , 2 moles of aluminium gives 3 moles of hydrogen gas.
Then 0.1333 moles of aluminium will give:
of hydrogen gas
Volume of 0.2 moles of hydrogen gas at STP = V
Temperature at STP = T = 298.15 K
Pressure at STP = P = 1 atm
n = 0.2 mol
PV = nRT (Ideal gas equation)

The volume of hydrogen gas produced at STP is 4.90 liters.
Answer: D convection currents
Explanation:
The seafloor spreading is a phenomena that occurs due to liberation of heat from the convection currents generated in the mantle. It makes the earth crust more plastic and less dense. This happens at divergent plate boundaries. As the plates move apart, the less denser material rises. It leads to the formation of mountain and crust cracks.