10th
- Which of the following methods is suitable for preventing an iron frying pan from rusting? (a) Applying grease Correct option is (c) Applying a coating of zinc 2
- Which of the following pairs will give displacement reactions? (a) NaCl solution and copper metal Correct option is (d) AgNO₃solution and copper metal. 2
- What are alloys? answer An alloy is the homogeneous mixture of two or more metals or metals and non metals. For example brass is an alloy of copper and zinc. 1
- Which metals do not corrode easily? Metals which have low reactivity such as silver, gold does not corrode easily. 1
- Metallic oxides of zinc, magnesium and copper were heated with the following metals. Metal Zinc Magnesium Copper Zinc oxide No reaction Displacement No reaction Magnesium oxide No reaction No reaction No reaction Copper oxide... 1
- What chemical process is used for obtaining a metal from its oxide? A metal can be extracted from its oxide by the process of reduction. 2HgO_((s))→2Hg(I)+O_(2(g)) 1
- Name two metals which are found in nature in the free state. The metals at the bottom of the reactivity series are mostly found in free state. For example: gold, silver, and platinum. 1
- Define the following terms. (i) Mineral (ii) Ore (iii) Gangue (i) Mineral: The naturally occurring compounds of elements are known as Mineral. (ii) Ore: Minerals from which metals can be extracted profi... 1
- Why do ionic compounds have high melting points? Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these fo... 1
- (i) Write the electron-dot structures for sodium, oxygen and magnesium. (ii) Show the formation https://lh3.googleusercontent.com/-5mSXW7_RtTI/Ya5Dz_9aT9I/AAAAAAAAC3w/Hkz-fzukgAUfqc4kUOph7SW-qt6W6uTqACNcBGAsYHQ/image.png (i) The represe... 2
- What would you observe when zinc is added to a solution of iron (II) sulphate? When zinc is added to iron (II) sulphate then it will displace the iron from iron sulphate solution as shown in the following chemical react... 1
- Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Hydrogen gas is evolved when dilute hydrochloric acid is added to a reactive metal. When iron reacts with dilute H₂SO₄, iron (II) sulphate w... 1
- Samples of four metals A, B, C and D were taken and added to the following solution one by one. (i) B is most reactive metal. (ii) B will displace copper from copper sulphate. (iii) Arrangement of metals in the order of decreasing react... 1
- Write equations for the reactions of (i) iron with steam (i) Iron react with steam to form the metal oxide and hydrogen. 3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g) (ii) The reaction of calcium with water... 2
- Why is sodium kept immersed in kerosene oil? Sodium is high reactive element. If it is kept in open it can explosively react with oxygen to catch fire. Hence to prevent accidental damag... 1
- Explain the meanings of malleable and ductile. Malleable: Substances that can be beaten into thin sheets are called malleable. For example, most of the metals are malleable. Ductile: Subs... 1
- is a poor conductor of heat. Mercury and Lead 2
- is the best conductor of heat. Silver is answer 2
- can be easily cut with a knife. Sodium is answer 2
- is a liquid at room temperature. Mercury is the answer 2
- Give two important uses of washing soda and baking soda wo important uses of washing soda are: → It is used in glass, soap, and paper industries. → It is used to remove permanent hardness of water... 1
- What is a neutralization reaction? Give two examples. A reaction in which an acid and base react with each other to give a salt and water is termed as neutralization reaction.For Example: (i) Na... 1
- Plaster of Paris should be stored in a moisture-proof container. Explain why? Plaster of Paris should be stored in a moisture-proof container because the presence of moisture (or water) can cause its slow setting by br... 1
- A milkman adds a very small amount of baking soda to fresh milk. (a) Why does he shift the (a) The milkman shifts the pH of the fresh milk from 6 to slightly alkaline because in alkaline condition, milk does not set as curd easily.... 1