As per 2019 CBSE Question Paper Design
Class: 10th Class CBSE
Time Allowed: 3 Hours
Maximum Marks: 80
- The question paper comprises five sections: A, B, C, D and E. You are to attempt both the sections.
- All questions are compulsory.
- Internal choice is given in sections B, C, E and E.
- Question numbers 1 and 2 in sections A are one marks questions. They are to be answered in one words or in one sentence.
- Question numbers 3 to 5 in sections B are two marks questions. These are to be answered in 30 words each.
- Question numbers 6 to 15 in sections C are three marks questions. These are to be answered in about 50 words each.
- Question numbers 16 to 21 in sections D are five marks questions. These are to be answered in 70 words each.
- Question numbers 22 to 27 in sections E are based on practical skills. Each questions is a two marks question. These are to be answered in brief.
Question: 1. Will current flow more easily through a thick wire or thin of the same material when connected to the same source? Why? 
Answer: Current will flow more easily through a thick wire as a thick wire has lesser resistance than a thin wire.
Question: 2. Name two main abiotic factors, which affect the human environment. 
Answer: Temperature, Humidity
Question: 3. How does the electronic configuration of an atom relate to its position in the modern periodic table? 
Answer: Valence electron gives the group number; No of shells tells the period number.
An element “X” has mass number 35 and the number of neutrons, is 18. Identify the group number and period of “X”.
Question: 4. When two lenses of focal length +10 cm and -5 cm are placed in contact, then find the net power. 
f1 = +10 cm; Then, p1 = 1/f1(m) = 100/10 Dioptre = +10 D
f2 = -5 cm; Then, p2 = 1/f2(m) = 100/-5 Dioptre = -20 D
Net Power, P = p1+p2 = +10D – 20D = -10D
Question: What will happen when the leaf of sensitive plant in touched? Explain. (2 marks)
Answer: Its leaves get folded due to nastic movement of its leaflet.
Question: 6. (1). State Joule’s Law of heading.
(2). Name two devices where heating effect of current in utilized.
(3). What is the name given to the commercial unit of electrical energy? Express this unit in Joules. 
Answer: (2). In the electric fuse which is a safety device and in the heating elements of electric devices like toaster, electric iron, microwave, etc.
(3). It is Kilowatt hour (kwh); 1 kwh = 3.6 × 106 Joules.
(1). Justify the following statements:
(i). Tungsten is used exclusively for filament by electric lamps.
(ii). We do not use series arrangement for domestic circuits.
(2). A wire of resistance 8 Ω is bent in the form of a closed circle. What is the effective resistance between two points A and B at the ends of any diameter of the circle? 
- (i). Tungsten has higher resistance and higher melting point.
(ii). So that each appliance gets the required current according to its resistance value, when these are connected in parallel combination.
- In this arrangement two semicircles of wire will have 4 Ω resistance each and will get connected in parallel.
So, 1/R = 1/4 + 1/4 ⇒ 1/R = 1+1/4 = 2/4 = 1/2
So, R (effective resistance) = 2 Ω