<span>answer is A : attracted to the negative terminal of the voltage source
I think, that the "hole"moves as it captures a free electron leaving another hole in a slightly different place. The electron leaving leaves a net + charge, which is attracted to the negative terminal. Because the "hole" behaves as a positive charge it is attracted towards the negative terminal.</span>
When calcium carbonate is heated, it breaks down to form calcium oxide and carbon dioxide.
Thermal decomposition is the process in which heat is required.
It is also known as thermolysis.
It is processed in which a compound breaks into two or more products when the heat is supplied.
This reaction is used for the production of oxygen.
This reaction is also used for production of acidic as well as basic oxides.
CaCO3 on thermal decomposition gives:
CaCO3→CaO+CO2
CaO→ Basic oxide.
CO2→ Acidic oxide.
Explanation:
acid should be handled with caution because it is dangerous as it may burn the skin
Explanation:
CO2 is called as gas because it exist in single thermodynamics state i.e CO exist in gases state only at room temperature.
Answer: There are 
atoms of hydrogen are present in 40g of urea, 
.
Explanation:
Given: Mass of urea = 40 g
Number of moles is the mass of substance divided by its molar mass.
First, moles of urea (molar mass = 60 g/mol) are calculated as follows.
According to the mole concept, 1 mole of every substance contains 
atoms.
So, the number of atoms present in 0.67 moles are as follows.
In a molecule of urea there are 4 hydrogen atoms. Hence, number of hydrogen atoms present in 40 g of urea is as follows.
Thus, we can conclude that there are atoms of hydrogen are present in 40g of urea, .
