The teacher instructed three students ‘A’, ‘B’ and ‘C’ respectively to prepare a 50% (mass by volume) solution of sodium hydroxide (NaOH). ‘A’ dissolved 50g of NaOH in 100 mL of water, ‘B’ dissolved 50g of NaOH in 100g of water while ‘C’ dissolved 50g of NaOH in water to make 100 mL of solution. Which one of them has made the desired solution and why?
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Write down the formula of (i) sodium oxide (ii) aluminium chloride (iii) sodium suphide (iv) magnesium hydroxide
(i) Sodium oxide → Na2O (ii) Aluminium chloride → AlCl3 (iii) Sodium suphide → Na2S (iv) Magnesium hydroxide → Mg(OH)2
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The difference in the mass of 100 moles each of sodium atoms and sodium ions is 5.48002 g. Compute the mass of an electron.
A sodium atom and ion, differ by one electron. For 100 moles each of sodium atoms and ions there would be a difference of 100 moles of electrons. Mass of 100...
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During an experiment the students were asked to prepare a 10% (Mass/Mass) solution of sugar in water.
(a) No. Mass % = Mass of solute Mass of solute + Mass of solvent ×100 (b) Solution made by Ramesh Mass % = 10/ 100 +10 x 100 = 10 /110 x100 =...
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Calculate the mass of sodium sulphate required to prepare its 20 persent (mass percent) solution in 100g of water?
Let the mass of sodium sulphate required be = x g The mass of solution would be = (x +100) g x g of solute in (x + 100) g of solution 20%...
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Gurmit wanted to perform Activity 16.8 using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teacher's advice?
Laser light is harmful for the human eyes, because its intensity is very high. It can cause damage to the retina and lead to blindness. Hence, it is advisable not...
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Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution.
Turmeric is yellow in colour. When a base is added to it, the solution turns into pink colour. However turmeric remains yellow when an acid or neutral solution is added...
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Rahul got a bike on his 18th, birthday from his parents. His father instructed him to always wear helmet while driving.
(i) He may get head injury that may even prove fatal to him. (ii) Brain, Eye. (iii) Obeying traffic rules while travelling on the roads, be careful while driving, obeying instructions by...
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In a group of students 100 students know Hindi, 50 know English and 25 know both. Each of the students knows either Hindi or English.
Let U be the set of all students in the group. Let E be the set of all students who know English. Let H be the set of all students who know...
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A teacher on attempting to arrange the students for mass drill in the form of a solid square found that 24 students were left over
Let the side of the square be x. No. of students = x2 + 24 New side = x + 1 No. of students = (x + 1)2 – 25 APQ => x2 +...
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write chemical equation of the reaction of ethanoic acid with the following : (i) Sodium (ii) Sodium hydroxide (iii) Ethanol
(i) 2CH3COOH + 2Na → 2CH3COONa + H2 Sodium ethanoate (ii) CH3COOH +...
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