10th Science Pre-Board Question Paper (2018-19)
Time: 3 hours
Subject Code: 086
- The question paper comprises two sections, A, B, C, D and E. You are to attempt both the sections.
- All questions are compulsory.
- All questions of Section A, B, C, D and E are to be attempted separately.
- Question numbers 1 & 2 in Section- A are 1 mark question. They are to be answered in one word in one sentence.
- Question numbers 3 to 5 in Section- B are 2 marks questions. These are to be answered in 30 words each.
- Question numbers 6 to 15 in Section-C are 3 marks questions. These are to be answered in about 50 words each.
- Question numbers 16 to 21 in Section-D are 5 marks questions. These are to be answered in 70 words each.
- Question numbers 22 to 27 in Section-E are based on practical skills. Each question is a two marks question. These are to be answered in brief.
Question: 1. List two advantages of water harvesting at the community level. 
Question: 2. State two sources of magnetic field. 
Question: 3. A pencil when dipped in water in a glass tumbler, appears to be bent at the air-water interface. Give reason for the following, along with a diagram. 
- How much work will be done in bringing a charge of 2 × 10-3 coulombs from infinity to a point P at which the potential is 5 V?
- How can three resistors of resistance 2Ω, 3Ω and 6Ω be connected to give a total resistance of 4Ω. 
Question: 5. From the following elements: 4Be, 9F, 19K, 20Ca
- Select two elements of the same group. Give justification for your selection.
- Write the formula and mention the nature of the compound formed by the union of K and element X (2, 8, 7) 
Question: 6. Write in brief how does a hydro power plant works. Give one advantage and one disadvantage of the same. 
- Name and state the law which relates the angle of incidence and refraction for refraction between a pair of media.
- The refractive indices of kerosene, turpentine oil and water are 1.44, 1.47 and 1.33 respectively. Which of the following medium has (i) maximum optical density, (ii) maximum speed of light?
- Calculate speed of light in kerosene, given speed of light in vacuum is 3 × 108 m/s. [1+1+1]
- Explain an activity to show that a current carrying conductor experiences a force when placed in a magnetic field.
- What change in the deflection of the compass needle at a point near current carrying straight conductor shall be observed in the:
(i) Current through the conductor is increased?
(ii) direction of current in the conductor is reversed? 
- State the role of plant hormones. Name a plant hormone which is essential for cell division.
- Name and explain the role of plant hormone involved in phototropism. [1+2]
- Identify the gland that secrete (a) insulin and (b) thyroxin.
- Explain with the help of an example how the timing and amount of hormone secreted are regulated in a human body. [1+2]
- Planaria, insects, octopus and vertebrates all have eyes. Can we group eyes of the animals together to establish a common evolutionary origin? Justify your answer.
- “Birds have evolved from reptiles”. State evidence to prove the statements. [2+1]
- How is ozone formed in the upper atmosphere? State how it affects an ecosystem.
- List two changes one can make in his/her habits to become more environment friendly. [2+1]
- Draw electron dot structure of sodium oxide.
- Different between ionic and covalent compounds. (2 points each)
- Write preparation of a salt used for bleaching clothes. [1 × 3 = 3]
- Explain different types of decomposition reactions with examples.
- ZnO + CO → Zn + CO2. Identify the reduced and oxidized substance. [2+1]
- How are metals of high reactivity extracted from their ores?
- Differentiate between calcination and roasting. Also give examples. [1.5+1.5]
- Explain why the sun appears reddish early in the morning.
- Why don’t the planets twinkle?
- Draw ray diagrams to show the defect and correction for a person suffering from far-sightedness. [1.5+1.5+2]
- Two resistances when connected in parallel given result value of 2 ohm, when connected in series the value becomes 9 ohm. Calculate the value of each resistance.
- An electric iron has a rating of 750 W, 220 V. Calculate:
(i) the current passing through it, and
(ii) its resistance, when in use. [3+2]
- Why metallic character increases on moving down the group?
- How does atomic size of element vary while going from left to right along a period in the Modern periodic table?
- Explain giving example that number of valence electrons in a group are same.
- Why are group 18 elements considered as inert?
- Explain Dobereiner’s Triad. [5×1 = 5]
- Write a chemical equation to covert ethanol to ethanoic acid.
- Explain the esterification and saponifications reactions along with their equations.
- Explain the mechanism for cleansing action of soap with the help of a diagram. [1+2+2]
- Draw a sectional view of the human alimentary canal and label the following parts:
(a) Oesophagus (b) Liver (c) Pancreas (d) Stomach
- What is meant by term peristalsis? [4+1]
- Write the functions of the following in human female reproductive system Ovary, Oviduct and Uterus.
- What is placenta? State its major role in case of a pregnant human female. [3+2]
Section B (Practical questions)
Question: 22. Draw the ray diagram when a light ray is incident on a glass prism. Mention clearly the angle of incidence, emergence and deviation. 
Question: 23. In a voltmeter, there are 20 divisions between the 0 marks an 0.5 V mark. What is the least count of the voltmeter? How is it connected in circuit? 
Question: 24. What is hard and soft water? How can we check hardness of water? 
Question: 25. Write reaction involved between HCl and NaOH individually with
- Zn metal
- NaHCO3