Explanation:
1. Thermochemical equation is balance stoichiometric chemical equation written with the phases of the reactants and products in the brackets along with the enthalpy change of the reaction.
The given correct thermochemical reactions are:
2. Phase change affect the value of the enthalpy change of the thermochemical equation. This is because change in phase is accompanied by change in energy. For example:
In both reaction phase of water is changing with change in energy of enthalpy of reaction.
The answer to this ? is true
Answer: Mass of 
required to form 930 kg of iron is 1328 kg
Explanation:
To calculate the number of moles, we use the equation:
.....(1)
For iron:
Given mass of iron = 930 kg = 930000 g (1kg=1000g)
Molar mass of iron = 56 g/mol
Putting values in equation 1, we get:
The chemical equation for the production of iron follows:
By Stoichiometry of the reaction:
2 moles of iron are produced by = 1 mole of
So, 16607 moles of iron will be produced by = 
of
Now, calculating the mass of from equation 1, we get:
Mass of = 
Thus mass of required to form 930 kg of iron is 1328 kg
Answer:
THE LENGTH OF THE AIR COLUMN IS 9.5 CM
Explanation:
Taking the atmospheric pressure to be 760 mmHg;
When the capillary tube is held horizontally, the pressure of the tube is 760 mmHg
when the capillary tube is held vertically, the pressure increases by 4 cm = 40 mm
The new pressure of the tube is hence, 760 + 40 mmHg = 800 mmHg
Using the pressure forlmula;
P1 V1 = P2 V2
P1 A1 L1 = P2 A2 L2
where A1 and A2 is the area of the capillary tube and it is equal, it cancels out.
P1 l1 = P2 l2
l2 = P1 l1 / P2
l2 = 760 * 10 / 800
l2 = 9.5 cm
The length of the air in the tube is 9.5 cm.
