CBSE Class 10 Answered

Chapter 1 Chemical reactions and chemical equations:

1. Balance the following chemical equation

   b) Aluminium + Copper chloride à Aluminium chloride + Copper

   c)  Hydrogen + Chlorine à Hydrogen chloride

   d) Ammonium nitrate à Nitrous oxide + Water vapour

Chapter 2 Acids, Bases, and Salts

1. Five solutions A, B, C, D, and E, when tested with a universal indicator, showed pH as 4, 1, 11, 7 and 9 respectively.

Which solution is (a) neutral (b) strongly alkaline (c) strongly acidic (d) weakly acidic (e) weakly alkaline.

Arrange the pH in increasing order of hydrogen ion concentration.

2. What is a neutralization reaction? Give two examples

3. Dry hydrogen chloride does not turn blue litmus to red whereas hydrochloric acid does. Why?

4. Plaster of Paris should be stored in a moisture-proof container. Explain why?

Chapter 3: Metals and Non-metals

1. State two ways to prevent rusting of iron

2. Differentiate between metal and non-metals on the basis of their chemical properties.

3. What types of non-metals are formed when they combine with oxygen?

Chapter 4: Carbon and its Compounds

1.  Write the name and structure of an aldehyde with four carbon atoms in its molecule.   

2.  Name the functional group present in each of the following organic compounds: 

1.                i.      CH3COCH3   
2.              ii.      C2H5COOH  

3.  Give a test for experimentally distinguishing between an alcohol and a carboxylic acid and describe how these tests are performed?            

Chapter 5: Periodic Classification of Elements

1.  How were the positions of cobalt and nickel resolved in the modern periodic table?                  

2.  How does the electropositive character of elements change on going down in a group?                                                                         

3.  How does the metallic character of elements change along a period of the periodic table from the left to the right and why?                                                                  

1.  Atoms of eight elements in the A, B, C, D, E, F, G, and H have the same number of electron in their outermost shells. It was found that elements A and G combine to form an ionic compound. This ionic compound is added in a small amount to almost all vegetables and dishes during cooking. Oxides of elements A and B are basic in nature while those of elements E and F are acidic. The oxide of element D is, however, almost neutral. Based on the above information, answer the following questions:

(i)           To which group or period of the periodic table do these elements belong?

(ii)         What would be the nature of compound formed by a combination of elements B and F?

(iii)       Which two of these elements could definitely be metals?

(iv)        Which one of the eight elements is most likely to be found in the gaseous state at room temperature?

(v)          If the number of electrons in the outermost shell of elements C and G is 3 and 7 respectively, write the formula of the compound formed by the combination of C and G.