Some important questions of chemistry CBSE 10TH Class
Some important questions of chemistry CBSE 10TH Class
Question 1. What will be the suitable group in the periodic table for placing Lithium element which is having the atomic number 3?
Question 2. How does the metallic character of the elements of group I changes as we if we move downwards?
Question 3. How many groups and periods are there in the modern periodic table?
Question 4. Write the next higher homolog of each of the following compounds: (i) C2H4 (ii) C4H6
Question 5. What is the reason that carbon atom forms only covalent compounds?
Question 6. On what basis are the elements arranged in the periodic table?
Question 7. The atomic numbers of three elements A, B, and C are 12, 18 and 20 respectively. State, giving reason, which two elements will show similar properties.
Question 8. Write any two anomalies of the Mendeleev’s classification of elements.
Question 9. (i) Why does the soap lose its cleansing action when used in hard water?
(ii) What is hydrogenation of vegetable oils?
Question 10. Explain why a diamond has a high melting point?
Question 11. Discuss the variance of valency and metallic character of elements when moving from left to right in a period?
Question 12. Explain why graphite is used as a lubricant?
Question 13. a) An organic acid X having the molecular formula CH4O2 is a liquid which often freezes during winter time in cold countries. On warming it with methanol in the presence of a few drops of concentrated sulphuric acid, a compound Y with a sweet smell is formed. i) Identify X and Y. Also, write their formulae showing the functional group present on them. ii) Write the chemical equation for the reaction involved.
Question 14. Write the name and general formula of a chain of hydrocarbons which undergoes an addition reaction with hydrogen. What are the essential conditions required for an addition reaction to take place? Also, write the chemical equation involved giving the name of the reactant and the product formed in such reaction.
Question 15. What do you mean by the functional group present in an organic compound?
Write the formula of the functional group presents the following compounds:
(a) Alcohol
(b) Aldehyde
(c) Ketones
(d) Carboxylic acid.
Question 16. A carboxylic acid (molecular formula C2H4O) reacts with an alcohol in the presence of an acid catalyst to form a compound 'X'. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives the same carboxylic acid C2H4O2. Identify the addition of ethanoic acid. In which of the test tube or test tubes the flame gets extinguished?
(a) X and Y
(b) Y and Z
(c) X and Z
(d) only Z
Question 22. 2 mL of acetic acid is added to a test tube containing an equal amount of distilled water and then after shaking its contents, the test tube is kept undisturbed for about 5 minutes. What will you observe in the test tube:
(a) A white precipitate settling at its bottom,
(b) A clear colorless solution,
(c) A layer of water over the layer of acetic acid, or
(d) A layer of acetic acid over the layer of water.
Question 23. While studying saponification reaction for the preparation of soap, the teacher suggested to a student to add a small quantity of common salt to the reaction mixture. The function of common salt in this reaction is to:
(a) Reduce the alkalinity of the soap,
(b) Reduce the acidity of the soap,
(c) Enhance the cleansing capacity of soap, or
(d) Favor precipitation of soap.
Question 24. Which among the following salts will give a light green colored solution when dissolved in water?
(a) CuSO4
(b) FeSO4
(c) ZnSO4
(d) Al2(SO4)3
Question 25. A student takes 5 ml of tap water in four test tubes and labels them as A, B, C, and D. Then he adds the same amount of four salts, potassium chloride in test tube A, calcium chloride in B, sodium chloride in C, and magnesium chloride in D. Lastly, he adds a few drops soap solution to the four test tubes. In which of the four test tubes formation of scum is observed?
(a) A and B
(b) B and C
(c) B and D
(d) A and D
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