Question

Statement 1 : oxyhydrogen flame produces higher temperature than oxy atomic hydrogen flame .
Statement 2 : the heat generated during the burning of these gases in oxygen is used to melt substances .
 $ A. $ statement 1 is true statement 2 is true . statement 2 is correct explanation of statement 1
 $ B. $ statement 1 is true. Statement 2 is true . statement 2 is not correct explanation of statement 1
 $ C. $ statement 1 is true , statement 2 is false
 $ D. $ statement 1 is false , statement 2 is true

Answer 1

Hint : The heat which is produced while a substance reacts with oxygen is called combustion . During the combustion the light is also produced which is either in the form of glow or as a flame. Mostly the substance which gets vaporised produces flame .

Complete step by step answer
This flame attends the combustion of hydrogen and oxygen . Hydrogen gas readily burns in oxygen and produces water . The heat release is about . The amount of heat produced is independent of mode of combustion; only the temperature of the flame varies . a mixture of oxygen ; hydrogen should be in the ratio of $ 1:2 $ at normal atmospheric pressure. It gets autoignition about $ {570^ \circ }C $ .
 To produce the mixture one needs to water electrolysis by using electric current .
William Nicholson was the first scientist to decompose water into pure hydrogen and oxygen in $ 1800 $ .
Atomic hydrogen is produced by dissociation of dihydrogen by using an electric arc. The process yields a huge amount of energy which can be used in welding or cutting steels . the energy produced by this is about $ 4000K $
The temperature produced by oxyhydrogen flame is about $ 2400K $ . This is very useful in torches to process refractory materials.
So, the first statement is wrong .
Correct statement will be the temperature produced by oxyhydrogen is lower than the temperature produced by oxy atomic hydrogen flame.
In the second statement the heat which is produced during this process is used to melt substance because the heat produced is very high which is sufficient for melting substance and also for cutting steels .
Statement D is correct .

Note
In flame there are three zones : outer zone which is blue in colour and also the hottest part of the flame , middle part is yellow which is moderately hot and the inner zone is least hot which is black in colour .