Formatting page ...
VASUDEV C. WADHWA ARYA VIDYA MANDIR, BANDRA EAST Pre-Preliminary Examination, January 2021 STD: X CHEMISTRY- Science Paper 2 Marks: 80 SC.2 (CHEM) DATE: 25/01/2021 Time: 2 hrs. Answer to this paper must be written on the paper provided separately. You will not be allowed to write during the first 15 mins. This time will be spent in reading the question paper. The time given at the head of this paper is the time allotted for writing the answers. Attempt all the questions from Section I and any four from Section II. Intended marks for the questions or parts of the question are given in brackets [ ]. This paper consists of 7 printed pages. Please ensure the following:It is suggested to attempt the Terminal Review using only a Laptop or a Desktop (with a webcam). In case a mobile or tab is being used, please have an alternate device with a camera so that you are visible to the invigilator at all times. Camera must be kept on during the entire paper. Pre preliminary paper comprises two sections i.e. Section-A and Section-B. Each section will have to be uploaded separately in the space provided in the form with the necessary renaming of the file as mentioned in the form. If students encounter any problem accessing or submitting the review, he/she must inform the invigilator. SECTION I (40 Marks) (Attempt all questions from this section) Question 1 a). Choose the correct alternative from options A, B, C, D for each of the following: i. The bond formed between two atoms of Oxygen in the formation of Oxygen molecule is a________. A) Single covalent bond B) Triple Covalent bond ii. [10] C) Double covalent bond D) Ionic bond Vapour density of Carbon dioxide is _________. [At. Wt. :- C=12, O= 16] A) 44 C) 22 B) 28 D)14 iii. The _________ property of Sulphuric acid is depicted when white anhydrous mass is obtained on addition of concentrated Sulphuric acid to Blue vitriol. A) Non-volatile C) Acidic B) Dehydrating D) Oxidising iv. The drying agent used to dry Ammonia gas in its Laboratory preparation is _______________. A) Slaked Lime C) Phosphorous pentoxide B) Quick Lime D) concentrated Sulphuric acid 2 ...2 contd Std X Science paper-2 (Chemistry) Pre-Preliminary Review January 2021 v. Amongst the elements given below, the element with the least electronegativity is ____________ A) Chlorine C) Iodine B) Bromine D) Fluorine vi. Alum is an example of _______ A) Basic Salt B) Mixed Salt C) Double Salt D) Normal salt vii. The electrolyte which liberates reddish brown gas around the anode during its electrolysis in its molten state is: A) Lead (II) chloride C) Copper (II) oxide B) Copper (II) sulphate D) Lead (II) bromide viii. If an element X belongs to period 2 and Group VI A, then X has _________ shells and _____________valence electrons. A) two, two B) six, two C) six, six D) two, six ix. The functional group present in Acetic acid is _____________ A) Carbonyl B) Carboxyl C) Hydroxyl D) Alkyl x. Which of the following salt when treated with dilute Sulphuric acid, liberates a gas that turns moist Lead acetate paper silvery black? A) Sodium sulphite B) Sodium sulphide C) Sodium chloride D) Sodium carbonate b). From the list given below, select the word(s) required to correctly complete the blanks (1) to (5) in the following passage: [5] Note: words chosen from the list are to be used only once. Write only the answers. Do not copy the passage. [reddish brown, Ammonium, Nitrogen dioxide, hydroxyl, dirty green, Ammonia, acidic, alkaline] Nitrogen and Hydrogen gas combine in the presence of a catalyst (Finely divided Iron) to give (1) gas. When the above-mentioned gas is passed through water it forms a solution which will be (2) . in nature and the solution contains (3) . ions and (4) . ions. If Iron (III) sulphate is added to the above solution, it forms a (5) coloured precipitate of Iron (III) hydroxide. ...3 ...3 contd Std X Science paper-2 (Chemistry) Pre-Preliminary Review January 2021 c). State True or False. Rectify and rewrite the false statements by altering the [5] underlined word/s only. i) All Sodium, Nitrate and Ammonium salts are soluble in water. ii) Copper liberates Hydrogen from dilute Hydrochloric acid. iii) Concentrated Nitric acid oxidises Carbon to Nitrogen dioxide. iv) Lead (IV) oxide is also known as Red Lead. v) The General formulae of Alkenes is CnH2n. d). Give balanced chemical equation for each of the following conversions: [5] i. Methane to Methanal ii. Ammonia is added in excess to Chlorine iii. Action of dil. Hydrochloric acid on Zinc oxide iv. Ethyne to 1,2-Dibromo ethene v. Action of conc. Sulphuric acid on Sulphur. e). Distinguish between the following based on the conditions given in the [5] brackets: i) Ethene and Ethyne (Chemical test) ii) Potassium sulphite and Potassium carbonate (Chemical test) iii) Ionisation and Dissociation (Type of compound that undergoes the process) iv) Boron and Sulphur (position in the Modern Periodic table) v) Trend in Ionisation Potential and Atomic size (Down the Group) f). i) State the Chemical name of the Gas in each of the following reactions: - [3] A) This gas is released when concentrated Sulphuric acid is added to Rock salt. B) This gas burns in Oxygen with a green flame. C) This reddish brown gas is released when concentrated nitric acid is added to Copper metal. ii) State your observations: - [2] A) Ammonium chloride is added to Sodium hydroxide and heated. B) Potassium permanganate is added to conc. Hydrochloric acid. 4 ...4 contd Std X Science paper-2 (Chemistry) Pre-Preliminary Review January 2021 g. i. Write the IUPAC name of the following organic compounds: A) [3] B) C) g. ii. Three salt solutions X, Y, Z have pH values 2.3, 6.8 and 10.5 respectively. A) Which of these is a weak acid? B) Few drops of Phenolphthalein indicator are added to each of the salt [2] solutions. Which salt solution will turn Pink? SECTION II (40 Marks) (Attempt any FOUR questions from this section) Question 2: a). i) Calculate the percentage of water of crystallisation by weight present in Washing Soda crystals. (Sodium carbonate decahydrate) [Given - At. Wt: - Na = 23, C= 12, O=16, H=1] [3] ii) 500 ml of a gas P at s.t.p. weighs 0.45 g. Calculate the vapour density of the [2] gas P , if 1 lit of Hydrogen gas weighs 0.09 g at s.t.p. b). Write the structural formula of the following: i. 2,3- Dimethyl pentanoic acid ii. neo- Pentane iii. Methoxy ethane [5] iv. All Position isomers of Butanol ...5 ...5 contd Std X Science paper-2 (Chemistry) Pre-Preliminary Review January 2021 Question 3:a). [3] i). The diagram shows a simple arrangement of the Fountain experiment: A) B) Name the two gases you have studied which can he used in this experiment. What is the common property demonstrated by this experiment? ii). Calculate the volume at S.T.P. occupied by 6.023 x 1021 molecules of a gas. b). Some elements belonging to a short period of the Modern periodic table are : [2] [5] Mg, Si, Na, Ar, S and Cl. i. To which period the above elements belong to? ii. Which element of this period forms a strong alkali? Name the alkali. iii. Which element from the above will have zero electron affinity and Why? Question 4:a. i. Draw Electron dot cross diagram for the formation of the following compound/ ion: - b. A) Hydronium ion. [3] B) Calcium chloride [2] A metal X forms a volatile chloride containing 65.5% of Chlorine. If the vapour [5] density of this metal chloride is 162.5, find the Molecular formula of the Metal Chloride. (X=56, Cl= 35.5) Question 5 :a. i). Give scientific reason for the following: A) B) C) D) E) Nitric acid stains the skin yellow. Low current for a longer period of time is preferred during Electroplating with Nickel. Potassium bisulphate exhibits properties of an acid in the aqueous solution but Potassium sulphate does not. The oxidising power of elements increases from left to right in a periodic table. Dilute Sulphuric acid is prepared by adding Concentrated Sulphuric acid to water and not by water to Concentrated acid. [5] 6 ...6 contd Std X Science paper-2 (Chemistry) Pre-Preliminary Review January 2021 b) Answer the following questions related to the extraction of Aluminium from its main ore by the Baeyer s process followed by Electrolytic reduction: [5] i) Name the mail ore of Aluminium. ii) Give the balanced chemical equation showing dilution of Sodium aluminate. iii) What is the name of the specific process carried out in step (ii) iv) Give the electrolytic reaction taking place at Cathode in the Electrolytic reduction of Alumina. v) Graphite anode are continuously replaced during electrolytic reduction of Alumina. Justify. Question 6:a. If an element Q is a metal with a valency 2 and P is a non-metal with a valency 3, then answer the following questions: i) ii) iii) b. [5] Write an equation to show how Q forms an ion. If P is a diatomic gas, write a balanced chemical equation for the direct combination of P and Q to form a compound. Draw electron dot cross diagram to depict the formation of P molecule. The following table shows the tests a student performed on a salt. Based on the [3] observations provided, identify the cation and anion present in the salt. Chemical test Observation Conclusion To the given salt solution, A pale blue precipitate is The cation Ammonium hydroxide is added formed which dissolves in present in the in minimum quantity first and excess to form a clear inky given salt is (i) then in excess. blue solution. To the given salt solution, A gas with irritating odour is The anion concentrated Sulphuric acid is produced which fumes in moist present in the added air and gives dense fumes with given salt is (ii) Ammonia. Thus, the chemical formula of the salt is ____(iii)___. c. For the preparation of Hydrochloric acid in the laboratory : [2] (i) Why is direct absorption of Hydrogen chloride gas in water not feasible ? (ii) What special arrangement is done to dissolve Hydrogen chloride gas in water ? ...7 ...7 contd Std X Science paper-2 (Chemistry) Pre-Preliminary Review January 2021 Question 7:a). Arrange the following elements according to the instructions given in bracket:i) Mg2+, Cu2+, Na1+, H1+ (In the order of preferential discharge at the cathode) ii) Ethane, Methane, Ethyne, Ethene. (In the increasing order of the molecular [2] weight) [H = 1, C = 12] b). The figure given below shows the large-scale manufacture of Nitric acid: [4] i) Name the process of manufacture of Nitric acid. ii) Give the balanced chemical equation for the reaction occurring in the catalyst chamber. iii) Absorption tower is packed with layers of Quartz. Justify iv) Distillation cannot be used to concentrate Nitric acid beyond certain concentration. Justify c). Complete the following table: - [4] Electrolysis of Anode Cathode Electroplating with Ionic equation (i) Ion discharged(ii) Material used (iii) Observation (iv) Silver Electrorefining of Copper -------The End---------
|
