The preparation of water from hydrogen and oxygen gas is accompanied by:

Identify the correct representation of reaction occurring during chlor-alkali process

Which of the following properly is generally not shown by metals?

Which one of the following will decide whether something is alive:

Junction between two neurons is called

1 kilowatt hour (kWh) is equal to

Commercial electric motors do not use

Acid rain happen because

Pentane has the molecular formula C₅H₁₂ . It has

Element X forms a chloride with the formula XCl₂ , which is a solid a high melting point. X would most likely be in the same group of the Periodic Table as :

Balance the following chemical equation:
Fe(s) + H₂O(g) \(\rightarrow\) Fe₃O₄(s)  + H₂(g)

What is the role of a catalyst in a chemical 

Arun took a pale green substance X in a test tube, and heated it over a flame. He observed a color change along with evolution of two gases with the smell of burning sulphur
(a) Identify X.
(b) Identify the product formed.
(c) Write the equation.
(d) Identify the type of chemical reaction.

Which gas is usually liberated when an acid reacts with a metal?

What is the purpose of quenching steel?

What are two types of reducing agents used to reduce metal oxide?

Name the catalyst used in the manufacture of ammonia by Haber's Process.

Name the term for transport of food from leaves other parts of the plant.

Which pancreatic enzyme is effective in digesting proteins?

What is lymph?

Name the part of brain in which hypothalamus is located.

Name the hormone secreted by thyroid gland.

What are gustatory receptors?

Give the S.I. unit of electric current?

Should the heating element of an electric iron be made of iron, silver or nichrome wire?

A wire of resistance 10 ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle?

What kind of quantity is magnetic field?

Name the rule used to determine the direction of induced current.

Who discovered that mechanical motion can produce current?

Name the gas which is the major constituent of bio gas?

What are fossil fuels?

What is geothermal energy?

Name the functional group present in each of the following organic compounds:
(i) C₂H₅Cl
(ii) C₂H₅OH

Write the name and molecular formula of the first member of the homologous series of alkynes

What is the difference between two consecutive members in a homologous series in alkanes in terms of:
(i) Molecular mass,
(ii) Number of atoms of elements.

Chlorine, bromine and iodine form a Dobereiner's triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic mass of bromine.

Why was the system of classification of elements into triads not found suitable? 

State modern periodic law of classification of elements.

A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound Y.
(a) Write the chemical formulae of X and Y.
(b) Write a balanced chemical equation, when X is dissolved in water.

Mention any five uses of plaster of Paris.

Give two examples each of the metals that are good conductors and poor conductors of heat respectively. 

What health disorder may occur if the following hormones are not secreted properly?
(a) Growth hormone
(b) Insulin
(c) Thyroxine
(d) Testosterone

Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?

List any two differences between AC and DC.

Explain geothermal energy. How can it be harnessed to produce electrical energy?

In electron dot structure, the valence shell electrons are represented by crosses or dots.
a) The atomic number of chlorine is 17. Write its electronic configuration
b) Draw the electron dot structure of chlorine molecule

Why atomic number is considered to be appropriate parameter than atomic mass for classification of elements in a periodic table?

Write the steps for balancing the chemical equation for the formation of ammonia by the combination of nitrogen and hydrogen.

Define water of crystallisation with two examples. How will you prove their existence in the examples given by you? 

Mention the products produced when an acid reacts with a base. Give equation of an example of the reaction involved. What is this kind of reaction known as?

From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal.
(i) which reacts with water only on boiling and
(ii) another which does not react even with steam.

How are oxygen and carbon dioxide transported in human beings? How are lungs designed to maximize the area for exchange of gases?

Name the constituents of blood.Why white blood corpuscles are called 'soldiers of the body'?

Describe the central nervous system in human being under the following heads:
(i) Regions included
(ii) Three functions of any one region

Distinguish between voluntary and involuntary actions of our body.

Two lamps, one related 60W at 220 W at 220V and the other 40 W at 220 V, are connected in parallel to the electric supply at 220V.
(a) Draw a circuit diagram to show the connections.
(b) Calculate the current drawn from the electric supply.
(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.

(a) Distinguish between the terms "overloading and short circuiting" as used in domestic circuits.
(b) Why are the coils of electric toasters made of an alloy rather than a pure metal?

Distinguish between an electric motor and generator?

Distinguish between permanent magnet and electromagnet.

(a) What is a 'solar cell'?
(b) Why is biogas considered an ideal fuel for domestic use?
(c) Name a device in which controlled chain reaction is used.

(a) Why is the Solar Cooker box covered with a plane glass plate?
(b) Why is energy of water flowering in a river considered to be an indirect form of solar energy?
(c) How is the fission of nucleus brought about?

You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO₃, ZnCl₂ and H₂O. In which of the above containers theses solutions can be kept?

(a) Why is sulphuric acid called 'King of Chemicals'?

(b) Describe the three chemical reactions that take place during the conversion of sulphur dioxide to sulphuric acid in the 'Contact Process'.

(c) Why should water be never added drop wise to concentrated sulphuric acid?

(a) Write chemical equations for the reactions involved in obtaining pure alumina from the mineral bauxite which has impurities of iron oxide and silica.
(b) Draw a labelled diagram of the electrolytic tank cell used for the extraction of aluminium from alumina.

How do carbohydrates, proteins and fats get digested in human beings?

Nervous and hormonal system together perform the function of control and coordination in human beings. Justify the statement with the help of an example.

How will you conclude that the same potential difference exist across three resistors connected in a parallel arrangement to a battery?

(a) Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current carrying loop is brought near it.
(b) Describe some salient features of magnetic lines of field. 

Which is the process used to harness nuclear energy these days? Explain it briefly.

Esters are sweet-smelling substances and are used in making perfumes. Suggest some activity and the reaction involved for the preparation of an ester with well labeled diagram.

The Position of three elements A,B and C in the Periodic Table is shown below:

Giving reasons, explain the following :
(a)Element A is a non-metal.
(b)Element B has a larger atomic size than element C.
(c) Element C has a Valency of 1