All questions
- For an A.P., \(a = 2\) and \(d = 3\). Then \(t_5 = \) Answer: A. 14 t_n = a + (n-1)d , so t₅ = 2 + 4 × 3 = 14 . 1
- If the \(n\)th term of an A.P. is \(t_n = 3n + 2\), its common difference is Answer: C. 3 t_(n+1) - t_n = 3(n+1) + 2 - (3n + 2) = 3 . 1
- The sum of the first 20 natural numbers is Answer: D. 210 S_n = n(n+1)/2 = 20 × 21/2 = 210 . 1
- How many two-digit natural numbers are divisible by 3? Answer: C. 30 They form the A.P. 12, 15, ..., 99. 99 = 12 + (n-1)3 ⇒ n - 1 = 29 ⇒ n = 30 . 1
- Which term of the A.P. 10, 7, 4, ... is \(-20\)? Answer: C. 11th a = 10, d = -3 . 10 + (n-1)(-3) = -20 ⇒ n - 1 = 10 ⇒ n = 11 . 1
- The sum of the first \(n\) terms of an A.P. is \(S_n = n^2 + 2n\). Its 10th term is Answer: B. 21 t₁₀ = S₁₀ - S₉ = (100 + 20) - (81 + 18) = 120 - 99 = 21 . 1
- If \(2k + 1\), 13 and \(5k - 3\) are three consecutive terms of an A.P., then \(k = \) Answer: A. 4 For an A.P., 2 × 13 = (2k + 1) + (5k - 3) ⇒ 26 = 7k - 2 ⇒ k = 4 . 1
- Q.3 (vii) Answer the following questions with the help of the given diagram :[Diagram: a beaker of solution containing Ag+ and NO3– ions; a silver plate is the anode and an aluminium spoon is the cathode; both are connected to a cell.](a) Name the pr… Answer: (a) Electroplating (silver plating of the aluminium spoon). (b) The electrolyte is a solution of a silver salt (silver nitrate). Whe... 1
- Q.3 (viii) Complete the following table :Type of the satelliteFunction of the satelliteThe names of the Indian satellite series and their launch vehicles(a) .........................Fix the location of any place on the earth’s surface................… Answer: Type of the satelliteFunctionIndian satellite series and launcher (a) Navigation satelliteFix the location of any place on the earth... 1
- Q.4 (i) (a) Draw a neat labelled diagram of human eye.(b) What is the minimum distance of distinct vision for a normal human eye ?(c) Name the capacity of the eye lens to change its focal length as per need.(d) Name the defect of eye vision in which… Answer: (b) 25 cm; (c) power of accommodation; (d) presbyopia. (a) Diagram: draw the eyeball and label the cornea, iris, pupil, aqueous humo... 1
- Q.4 (ii) Atomic number of chlorine is 17.(a) Write the electronic configuration of chlorine.(b) What is the number of electrons in the valence shell of chlorine ?(c) Write the molecular formula of chlorine.(d) Name the type of bond in the formation o… Answer: (a) 2, 8, 7; (b) 7; (c) Cl₂; (d) a single covalent bond; (e) shown below. (a) K = 2, L = 8, M = 7, i.e. 2, 8, 7. (b) 7 electrons in... 1
- Q.1 (A)(i) A molecule of glucose is completely oxidised in aerobic respiration and molecules of H2O and ...................... are produced along with energy. Answer: A. CO2 Answer: (A) CO₂ mathrmC₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (38 ATP). O₂ is used up in respiration, not produced. 1
- Q.1 (A)(ii) Vinegar contains ...................................... acid. Answer: A. acetic Answer: (A) acetic Vinegar is a dilute solution of acetic acid (about 4–8%), made by fermentation of alcohol by Acetobacte... 1
- Q.1 (A)(iii) Any nucleotide of the gene suddenly changes its position that causes a minor change which is nothing but the ..................... Answer: B. mutation Answer: (B) mutation A sudden change in the sequence of nucleotides of a gene (DNA) is called a mutation. Such changes c... 1
- Q.1 (A)(iv) In humans, sperm production occurs in the .................... organ. Answer: C. testes Answer: (C) testes Sperms are produced in the seminiferous tubules of the testes. The vas deferens and the ducts only carr... 1
- Q.1 (A)(v) Solar photovoltaic cell converts the solar radiation energy directly into ........................... energy. Answer: D. Electrical Answer: (D) Electrical A solar photovoltaic (PV) cell, made of semiconductors such as silicon, converts sunlight direc... 1
- Q.1 (B)(i) Find the odd one out : Fragmentation, Regeneration, Budding, Fertilization. Answer: Fertilization Fertilization (fusion of male and female gametes) is part of sexual reproduction. Fragmentation, regeneration and budd... 1
- Q.1 (B)(ii) Write the correct co-relation : Diabetes : Insulin : : Cancer : ..................... Answer: Interferon Insulin made by biotechnology (recombinant DNA technology) is used to treat diabetes. In the same way, interferons produc... 1
- Q.1 (B)(iii) State whether true or false : Study of fossils is an important aspect of the study of evolution. Answer: True Fossils are palaeontological evidence of evolution. They show which organisms lived in different periods and how they changed o... 1
- Q.1 (B)(iv) Give any two commercial uses of Biotechnology. Answer: Production of medicines such as insulin and vaccines, and production of genetically modified (Bt) crops. Other uses: biofertilisers... 1
- Q.1 (B)(v) Being a fish, I perform respiration with the help of lungs. Who am I ? Answer: Lungfish (e.g. Protopterus) The lungfish is a fish that can breathe air with lung-like organs, besides gills. 1
- Q.2 (A)(i) Give scientific reasons : Sometimes, higher plants and animals too perform anaerobic respiration. Answer: When oxygen supply is insufficient, cells still need energy, so they respire anaerobically for a short time. Higher plants and anima... 1
- Q.2 (A)(ii) Give scientific reasons : It is not right to consider the mother responsible, for giving birth to a girl child. Answer: The sex of the child depends on the father’s sperm, not on the mother. A woman has XX sex chromosomes, so all her ova carry an X chr... 1
- Q.2 (A)(iii) Give scientific reasons : The energy generated from nuclear fuels is not environment friendly. Answer: Nuclear power produces radioactive waste and carries a risk of radiation leaks. The spent fuel and waste from nuclear power plants s... 1