Q. 1. HC1 and HNO3 both produce hydrogen ions in aqueous state. With metals they produce hydrogen gas. However, as HNO3 is a strong oxidising agent, it reacts with the hydrogen gas so produced during the reaction to form water. Thus, acids such as HC1, H2SO4 produce hydrogen gas with metals whereas, HN03 produce water.

Q. 2.

Minerals Ores Gangue
Substances that occur naturally in rocks and have their own characteristic appearance and chemical composition . Minerals, from which the metals can be profitably extracted, are called ores. Waste materials, which are mixed in the valuable ores.
All minerals are not ores. All ores are minerals.

Q. 3. Metal A is Zn.

It reacts with blue copper sulphate to form colourless zinc sulphate.
Zn(s)+CuSO4 (aq)? ZnSO4 (aq)+Cu(s)?
Copper sulphate zinc sulphate (Brown)
(Blue) (Colourless)
It reacts with green iron sulphate to produce colourless zinc sulphate.
Zn(s)+FeSO4 (aq)?ZnSO4 (aq)+Cu(s)?
Ferrous sulphate zinc sulphate (Brown)
(Green) (Colourless)
Zn does not react with aluminium hydroxide, as Zn is less reactive than Al, hence it cannot displace it.

Q. 4. Highly reactive elements are obtained by the electrolysis of their molten chlorides. The metals are deposited at the cathode, whereas, chlorine is liberated at the anode. In the case of sodium chloride, the reactions are: At cathode, Na+ + e- ? Na At anode, 2Cl- ? Cl2 + 2e- Similarly, aluminium is obtained by the electrolytic reduction of aluminium oxide. Carbon cannot be used for the reduction of highly reactive metals because these metals have more affinity for oxygen than carbon. These metals are obtained by electrolytic reduction.

Q. 5. Electrolytic refining is the process of obtaining metals of very high purity by depositing the desired metal and the impure metal on different electrodes in an electrolytic cell. Metal obtained after reduction are not very pure, so they need to be refined further. The most widely used method is electrolytic refining. For example, in the electrolytic refining of copper, CuSO, is acidified (to make it highly conducting) and is used as electrolyte. The anode is made of thick impure copper rod, whereas the cathode is made of thin pure copper. Anode is connected to positive terminal of the battery whereas cathode is connected to the negative terminal of the battery. Pure metal is obtained at cathode.





Q. 6. Corrosion is the wearing away, dissolving, or softening of any substance which takes place due to chemical or electrochemical reaction with its environment. It applies to the gradual action of natural agents, such as air or salt water, on metals. It is rather a slow process. Four methods used to prevent from corrosion are:

Painting, Oiling or Greasing: It protects the metal from corrosion by forming a layer, which cuts off the exposure to moisture and air.
Anodising: Process of coating a metal, e.g., aluminium, with a protective or decorative oxide by making the metal the anode of an electrolytic cell .
Galvanising: It is a method of depositing a thin layer of zinc over steel and iron objects. The galvanised articles remain protected even if zinc coating; .s broken.
Alloying: Most of the metals are used as alloys—that is, mixtures of several elements—because these are superior to pure metals in their properties and uses. Alloying is done for many reasons. It helps in increasing strength, making articles corrosion resistance, or reduce costs.


Paper Submitted By Mr. Basant
Email Id : basant.physics@gmail.com
Ph No. : 9777702608

Q. 1. Draw the ray diagram for an object placed at 2F in front of convex mirror.

Q. 2. Explain the different types of energy that can be obtained from
oceans.

Q. 3. What is the principle used in motors and discuss the role of split rings in electric motors.

Q. 4. Magnification of object is –1 . What kind of spherical mirror is Used and what is position of the object.

Q. 5. Hydrogen has been used as rocket fuel. Is it cleaner than CNG? why or why not.

Q. 6. Explain the construction ,working ,advantages and disadvantages of using solar cooker with diagram.

Q. 7. How has the traditional use of wind and water energy been modified for our convenience.

Q. 8. Find the equivalent resistance between A and B and find current In 5 ohm resistance

Q. 9. Why dispersion of light is found in case of prism and not in glass Slab. From the diagram give the number that corresponds to color Of danger signal. Why only that color is used as danger signal.

Q. 10. A convex lens has focal length of 50 cm. What is its power ? An object is kept at distance of 75 cm from this lens. Where Is the image formed ? How does size of image compare with that of object ?

Q. 11. Explain house hold wiring system with diagram. Explain the terms

over loading
short circuiting
earthing
fuse


Paper By Mr. Sarvir
Email Id :loveysarvir@yahoo.co.in
Ph No. : 09815257573

Q. 1. why is dna copying essential for reproduction?

Q. 2. what is the role of a catalyst in a chemical reaction?

Q. 3. which class of compounds gives a positibve fehling’s test? Ans:aldehydes

Q. 4. what is meant by 1 volt?

Q. 5. write the chemical name and formula for bleaching powder?

Q. 6. What is meant by dehydrating agent?

Q. 7. state ohm’s law.draw a schematic diagram of the circuit for studying ohm’s law?

Q. 8. state one limitation for the usage of solar energy?

Q. 9. what is a gene and where is it located?

Q. 10. explain double fertilization in plants?

Q. 11. What is meant by magnetic field?

Q. 12. why chlorophyll green in colour?

Q. 13. give two methods to prevent rusting?

Q. 14. state the functions of gastric glands? 15.explain why stars twinkle?

Paper By Geetha
Email Id : aasritha2006@yahoo.co.in

Q.1. What is meant by thermal decomposition?

Q.2. Name the group of chemical substances used to prevent oxidation.

Q.3. What is the nature of oxides formed by metals and non metals?

Q.4. Name one cheap reducing agent commonly used in extraction of pure metals.

Q.5. Define catenation.

Q.6. Name the gas evolved when sodium carbonate or sodium bicarbonate reacts with ethanoic acid?

Q.7. Name the cells which regulate the opening and closing of stomata.

Q.8. Name the enzyme responsible for changing starch to sugar in mouth.

Q.9. What is scum?

Q.10. Which type of flame is produced by saturated hydrocarbons on incomplete combustion?

Q.11. What happens when calcium oxide reacts with water? Write the chemical equation of reaction involved.

Q.12. Respiration is considered an exothermic reaction. Explain?

Q.13. Give reason:- Ionic compounds conduct electricity only in molten state not in solid state.

Q.14. Explain why:-

Aluminium is more reactive than Iron, yet its corrosion is less than Iron.
Carbonate and sulphide ores are usually converted into oxides before reduction during process of e extraction.
Q.15. What is hydrogenation? Write its industrial application.

Q.16. Write the common name of ethanoic acid. What is its ditute solution (5-8%) in water known as?

Q.17. Write the functions of muscular wall in digestive tract.

Q.18. Why danger signals are red?

Q.19. Explain the phenomenon which causes twinkling of star.

Q. 20. An object of 4cm height is placed at a distance of 15cm away from a convex lens of focal length 10cm.
Find the nature, size, position of the object. Find its magnification.

Q. 21. Draw and explain the ray diagram formed by a convex mirror when

object is at infinity.
object is at finite distance from the mirror.
Q. 22. Name three refractive defects of vision with the help of diagram. Explain the reasons and correction of these d defects.

Q. 23. Describe the urine formation in human beings. Draw a neat and labelled diagram of nephron.

Q. 24. What are soaps? Explain the mechanism of the cleaning action of soaps? Soaps form scum (insoluble s substance) with hard water. Explain why? How this problem is overcome by use of detergents?

Q. 25. What are ionic compounds. State four properties of ionic compounds in respect to their physical nature, melting and boiling points, solubility and conduction of electricity?