CBSE ADDA

CBSE TEST PAPER :Chapter Metal and non metal                                                                                                                Section _A _1 marks 1. The lowest temperature at which a Substance catches fire is called its- 2. In a soda-acid type fire extinguisher………. Reacts with sulphuric acid to give out carbon dioxide. 3. Explosion is the evolution of –-------- and ------- 4. Substance which vaporise during Burning gives ------- 5. Yellow colour in the flame denotes ------ zone 6. Fe(OH)2 + O2 + H2O ---> ---------------- 7. The rocky impurities, including silica and earthly particles, present in an ore are called------ 8. ---------- is the only liquid non-metal at room temperature. 9. The property by which an element can be beaten into thin sheets is called------ 10. ----- react at room temperature so it is stored under kerosene to prevent its reaction with oxygen, moisture and carbon dioxide present in air.                              

 (Q.) What is magnetic field? (2 Marks) (Ans) The region around the magnet, where force of attraction or repulsion can be felt by magnetic materials, is called as magnetic field. (Q.) What will be the frequency of an alternating current, if its direction changes after every 0.05 s?  (Ans) The time period (T) of one cycle would be = 2 x (0.05 s) = 0.1 s. frequency, f = 1/T. Hence, f = (1 / 0.1) = 10 Hz. (Q.) What is the principle on which working of electric generator is based? What are its important parts?  (Ans) The working of electric generator is based on the principle of electromagnetic induction. Important parts of electric generator are armature, slip rings, brushes and field magnets. (Q.) Why two magnetic lines of force don’t intersect each other?   (Ans) If so then at the point of intersection there will be two different directions of magnetic field which is not possible. ( Q.) Give two methods

Q.1 Why is carbon tetravalent ? Ans 1:Carbon atom has 4 electrons in the outermost shell.It needs 4 more electrons to complete its octet. Therefore , carbon is tetravalent .  Q.2 The formula of a hydrocarbon is Cn H2n. Name the family to which it belongs and also predict its nature.   Ans 2: The hydrocarbon belongs to alkenes It is unsaturated in nature .  Q.3 What is the valency of carbon in CH3-CH3, CH2=CH2 and HC=CH ?  Ans 3: The valency of carbon in all its compounds whether saturated or unsaturated is 4.  Q.4 Out of butter and ground nut oil , which is unsaturated in Nature?  Ans 4: Groundnut oil is unsaturated in nature .  Q.5 Why is high temperature not favourable for alcoholic fermentation?  Ans 5: The high temperature destroys the enzymes which are needed to carry fermentation .  Q.6 Name a cyclic unsaturated hydrocarbon, containing three double bonds?   Ans 6: Benzene  Q.7 What is the difference in the molecular mass of any two adjacent homologues?  Ans 7 : 14 ma

VERY SHORT ANSWER QUESTIONS CARRYING 1 MARK WITH ANSWER Q.1 A straight wire carrying electric current is moving out of plane of paper and is perpendicular to it. What is the direction and type of induced magnetic field lines ? Answer: Induced magnetic field lines will be in the form of concentric circles in the plane of paper. Q.2 How can it be shown that magnetic field exist around a wire carrying current? Answer: By using magnetic compass which shows deflection Q.3 How can a solenoid be used to magnetise a steel bar. Answer: By inserting the steel bar inside the solenoid and switching on electric current Q.4 Why can’t two magnetic field lines ever intersect? Answer: If so then at the point of intersection there will be two different directions of magnetic field which is not possible. Q.5 Can a 5 A fuse be used in wire carrying 15 A current? Why? Answer: No, because it would then be ineffective in controlling the amount of current flowing. Q.6 Give the fac