Answer: The correct option is 2.
Explanation: Group 15 elements are Nitrogen, phosphorous, Arsenic, Antimony, Bismuth.
To know whether an element exits as a diatomic molecule or not, we look at the atomicity of an element.
Atomicity is the number of atoms of an element combining to form a molecule.
Atomicity of Nitrogen = 2
Atomicity of Phosphorous = 4
Atomicity of Bismuth = 1
Atomicity of Arsenic = 1
The element having atomicity 2 will exist as a diatomic molecule.
Hence, Nitrogen is a diatomic molecule 
Combustion.
Anytime a reaction has CO2+2H2O, it's combustion
We are given the number of moles:
O = 1.36 mol
H = 4.10 mol
C = 2.05 mol
To get the empirical formula, first divide everything by
the smallest number of moles = 1.36 mol. So that:
O = 1 mol
H = 3 mol
C = 1.5 mol
Next step is to multiply everything by a number such that
all will be a whole number. In this case, multiply by 2 to get a whole number
for C, so that:
O = 2 mol
H = 6 mol
C = 3 mol
Therefore the empirical formula of the compound is:
C3H6O2
Answer:
Explanation:
13 ) symbol of enthalpy change = Δ H .
14 ) enthalpy change is nothing but heat absorbed or evolved .
During fusion enthalpy change
Δ H .= m Lf , m is mass and Ls is latent heat of fusion
During evaporation, enthalpy change
Δ H .= m Lv , m is mass and Lv is latent heat of evaporation
during temperature rise , enthalpy change
Δ H = m c Δ T
In case of gas , enthalpy change can be calculated by the following relation
Δ H = Δ E + W , Δ E is change in internal energy , W is work done by gas.
15 ) When enthalpy change is negative , that means heat is released to the environment .So reaction is called exothermic .
when heat is absorbed enthalpy change is positive . Reaction is endothermic.
Simple,
take a look at your periodic table, if you have it labeled look at the Halogen
Group, it includes: Flourine, Chlorine, Bromine, Iodine, and Astatine.
Now, a period on the periodic table is read from left to right, and goes
down the rows of the periodic table.
Go to Period 5, go all the way to the Halogens, what is there?
Iodine.
Thus, your answer.
