Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : The alkali metals and their salts impart characteristic colour to reducing flame.
Reason R : Alkali metals can be detected using flame tests.
In the light of the above statements, choose the most appropriate answer from the options given below :
Potassium dichromate acts as a strong oxidizing agent in acidic solution. During this process, the oxidation state changes from :
Based on the given figure, the number of correct statement/s is/are __________.
A. Surface tension is the outcome of equal attractive and repulsive forces acting on the liquid molecule in bulk.
B. Surface tension is due to uneven forces acting on the molecules present on the surface.
C. The molecule in the bulk can never come to the liquid surface.
D. The molecules on the surface are responsible for vapour pressure if the system is a closed system.
28.0 L of CO$$_2$$ is produced on complete combustion of 16.8 L gaseous mixture of ethene and methane at 25$$^\circ$$C and 1 atm. Heat evolved during the combustion process is ___________ kJ.
Given : $$\mathrm{\Delta H_c~(CH_4)=-900~kJ~mol^{-1}}$$
$$\mathrm{\Delta H_c~(C_2H_4)=-1400~kJ~mol^{-1}}$$