List of top Science Questions on Organic Chemistry asked in CBSE Class X

In the following experimental setup of electrolysis of water, if P and Q are the gases collected in the test tubes enclosing the electrodes R and S, then select the option/options in which the matching is correct: 
(i) P - Oxygen gas, R - Anode 
(ii) P - Hydrogen gas, S - Cathode 
(iii) Q - Hydrogen gas, R - Cathode 
(iv) Q - Oxygen gas, S - Anode 

You have three aqueous solutions A, B, and C as given below: 
A - Potassium nitrate 
B - Ammonium chloride 
C - Sodium carbonate 
The ascending order of the pH of these solutions is:

A hydrocarbon which does not belong to the same homologous series of carbon compounds is

Juice of tamarind turns blue litmus to red. It is because of the presence of a chemical compound called: 

The water of crystallization is present in:

Assertion (A): Carbon and its compounds are our major sources of fuels. 
Reason (R): Most of the carbon compounds on burning release a large amount of heat and light.

A light green coloured solution of sulphate salt of metal 'P' is taken in a beaker, a rod of another metal 'Q' is put in this solution as shown in the following figures: 

One mole of a hydrocarbon, on combustion in air, produces two moles of \( \text{CO}_2 \), two moles of \( \text{H}_2\text{O} \), and a large amount of heat. This hydrocarbon is:
Consider the following organic compounds:
\(\text{C}_2\text{H}_5\text{CHO}, \text{CH}_3\text{COOH}, \text{C}_2\text{H}_5\text{OH}, \text{CH}_3\text{COCH}_3\)
Give the chemical equation for the chemical reaction when \(\text{CH}_3\text{COOH}\) and \(\text{C}_2\text{H}_5\text{OH}\) react in the presence of conc. \(\text{H}_2\text{SO}_4\).
Consider the following organic compounds:
\[ C_2H_5CHO, \, CH_3COOH, \, C_2H_5OH, \, CH_3COCH_3 \]
Which one of these compounds, when heated at 443 K in excess conc. \(\text{H}_2\text{SO}_4\), forms ethene as its major product? State the role of conc. \(\text{H}_2\text{SO}_4\) in the reaction. Also, write the chemical equation for the chemical reaction involved.
The structural formula of Cyclohexane is
Write the formula and the molecular mass of the third homologue of alcohols. State how the boiling point of an alcohol changes as one moves from lower to higher homologues.
Carbon is a versatile element that forms the basis of all living organisms and many of the things we use. A large variety of compounds is formed because of its tetravalency. Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements.
Answer the following questions :
(A) (i) Define a homologous series of carbon compounds.
(ii) Why is the melting and boiling points of \(C_4H_8\) higher than that of \(C_3H_6\) or \(C_2H_4\)?
(iii) Why do we NOT see any gradation in chemical properties of a homologous series compounds?
(iv) Write the name and structures of (i) aldehyde and (ii) ketone with molecular formula \(C_3H_6O\).

OR

(B) (i) Write the name and structure of an organic compound ‘X’ having two carbon atoms in its molecule and its name is suffixed with ‘-ol’.
(ii) What happens when ‘X’ is heated with excess concentrated sulphuric acid at 443 K? Write chemical equation for the reaction stating the conditions for the reaction. Also state the role played by concentrated sulphuric acid in the reaction.
(iii) Name and draw the electron dot structure of hydrocarbon produced in the above reaction.