12 times breathe give 240 ml of pure 
. Each breathe gives 20 ml of .
Let us consider, volume of air per breathe= x ml.
Pure from inhaled air= 
ml and Pure from exhaled air= 
ml.
Pure from inhaled and exhaled air= 20 ml
So, + = 20
Therefore, x = 55.5 ml
So, volume of air per breath= 55.5 ml.
Answer:
<u>Oxidation state of Mn = +4</u>
Explanation:
Atomic mass of Mn = 55g/mol
From Faraday's law of electrolysis,
Electrochemical equivalent = 
i.e Z = 
= 
= 0.0001424 g/C
But Equivalent weight, E = atomic mass ÷ valency = Z × 96,485
⇒ 
= 0.0001424 × 96,485
<u>∴ Valency of Mn = +4</u>
Combustion is a chemical reaction between a fuel and an oxidant, oxygen, to give off combustion products and heat. Complete combustion results when all of the fuel is consumed to form carbon dioxide and water, as in the case of a hydrocarbon fuel. Incomplete combustion results when insufficient oxygen reacts with the fuel, forming soot and carbon monoxide.
The complete combustion of propane proceeds through the following reaction:
+
-->
+
Combustion is an exothermic reaction, which means that it gives off heat as the reaction proceeds. For the complete combustion of propane, the heat of combustion is (-)2220 kJ/mole, where the minus sign indicates that the reaction is exothermic.
The molar mass of propane is 44.1 grams/mole. Using this value, the number of moles propane to be burned can be determined from the mass of propane given. Afterwards, this number of moles is multiplied by the heat of combustion to give the total heat produced from the reaction of the given mass of propane.
14.50 kg propane x <u> 1000 g </u> x <u> 1 mole propane </u> x <u> 2220 kJ </u>
1 kg 44.1 g 1 mole
=
729,931.97 kJ
