Science
- Buttermilk spoils if kept in a copper or brass container. Buttermilk spoils if kept in a copper or brass container because Brass or copper reacts with organic acid. Buttermilk contains lactic acid a... 1
- Hydronium ions are always in the form H3 O+ The strength of an acid is measured in terms of the extent of the dissociation of acid in an aqueous solution. The higher H⁺ ion concentrati... 1
- Explain what is meant by electrolysis of water. Write the electrode reactions and explain them Electrolysis of water : When electric current is passed through water containing a few drops of an acid or a few drops of a base, it dissoci... 1
- What is meant by neutralization? Give two examples from everyday life of the neutralization reaction. Neutralization reaction : A neutralization reaction is a reaction in which an acid and a base reacts to form water and a salt. It involves t... 2
- Classify the acids according to their basicity and give one example of each type. The number of ionizable hydrogen (H⁺) ions obtainable by dissociation of one molecule of an acid is called its basicity For example : HCl --... 2
- Obtain a sample of rainwater. Add to it a few drops of universal indicator. Measure its pH. This is an activity based question in which you are supposed to collect rainwater from different places. If we take samples of rain water fr... 1
- Write down the concentration of each of the following solutions in g/L and mol/L. 4) 4.9 g H2SO4 in 200 mL solution Given: Volume of solution = 200ml =0.2L, Mass of CH₃COOH in gram =4.9g Molecular Formula = H₂SO₄ Molecular mass of H₂SO₄ = 2(H)+1(S)+4(O) =... 1
- Write down the concentration of each of the following solutions in g/L and mol/L. 3) 3g CH3COOH in 100 mL solution Given: Volume of solution = 100ml =0.1L, Mass of CH₃COOH in gram =3g Molecular Formula = CH₃COOH Molecular mass of CH₃COOH = 2(C)+2(O)+4(H)... 1
- Write down the concentration of each of the following solutions in g/L and mol/L. 2) 2g NaOH in 50 mL solution Given: Volume of solution = 50ml =0.05L, Mass of NaOH in gram =2g Molecular Formula = NaOH Molecular mass of NaOH = 23 +16 + 1 = 40m Mass of... 1
- Write down the concentration of each of the following solutions in g/L and mol/L. 1) 7.3g HCl in 100ml solution Given: Volume of solution = 100ml =0.1L, Mass of Solute in gram =7.3g Molecular Formula = HCL Molecular mass of HCl = 1+35.5=36.5 m Mass of... 1
- Show the dissociation of the following compounds on dissolving in water, with the help of chemical equation and (i) HCl underrightarrowwater H^(+ )+ Cl⁻ Dissociation is large (ii) NaCl underrightarrowwater Na⁺ + Cl⁻ Dissociation is large (iii) KOH unde... 2
- Formation of a magnesium chloride from magnesium and chlorine. Atomic number of Magnesium atom is 12. Electronic configuration is : Mg = 2, 8, 2 So it contains 2 valence electron. In order to achieve the... 1
- Formation of sodium chloride from sodium and chlorine. Atomic number of Sodium (Na) atom is 11. Electronic configuration is: Na = 2, 8, 1 So it contains 1 valence electron. In order to achieve th... 1
- Classify the following oxides into three types and name the types. CaO, MgO, CO2 , SO3 , Na2O, ZnO, Al2O3 , Fe2O3 1) Acidic Oxides: CO₂ (Carbon dioxide), SO₃ (Sulfur trioxide) 2) Basic Oxides: CaO (Calcium oxide), MgO (Magnesium oxide), Na₂O (Sodium oxid... 1
- Dilute H2SO4 was taken in an electrolytic cell and electric current was passed through it. When a dilute solution of sulfuric acid is electrolysed, gases are produced at both the anode and the cathode electrode. The gas produced at... 1
- Pieces of blue vitriol were heated in a test tube. On cooling, water was added to it. When pieces of blue vitriol are heated in a test tube, then crystal structure of blue vitriol broke down to form a colourless powder and wat... 1
- Dilute HCl was added to limestone. Limestone is calcium carbonate. When Dilute HCl was added to limestone, it forms calcium chloride, water and carbon dioxide gas. 2HCl + CaCO... 1
- Zinc oxide was added to dilute HCl and zinc oxide was added to dilute NaOH. When Zinc oxide is added to dilute HCl, it forms zinc chloride and water and neutralization reaction takes place. In this reaction zinc oxid... 1
- Magnesium oxide was added to dilute HCl and magnesium oxide was a added to dilute NaOH. Bases react only with oxides of non-metal to form salt and water and neutralization reaction take place. Magnesium oxide is a base. When Mag... 2
- A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred. When litmus paper is dipped into 2 mL of dilute HCl solution , then blue litmus paper is turned into red colour and there is no effect on re... 1
- Two or three filings of copper were added to 10ml dilute nitric acid and stirred. Answer: Copper dissolves slowly, the solution turns blue (copper nitrate forms), and a colourless gas, nitric oxide (NO), is given off, whic... 1
- Two drops of the indicator phenolphthalein were added to 10ml solution of sodium hydroxide. When two drops of Phenolphthalein indicator are added to 10 mL solution of Sodium hydroxide, then the solution turns light pink in colour be... 1
- 50ml water is added to 50ml solution of copper sulphate. Write down the changes that will be seen in each Answer: The blue colour of the solution becomes lighter (paler); no chemical reaction takes place. Copper sulphate solution is blue because... 1
- Identify the odd one out and justify. (a) Chloride, nitrate, hydride, ammonium (a) Chloride, nitrate, hydride, ammonium Answer Ammonium - Ammonium is odd because Ammonium is cation and rest are anions. (b) Hydrogen chlo... 1