Is it possible for a hydrogen ( H 1 1 ) nucleus to emit an alpha particle? Give a reason for your answer.

No, as alpha radiation is nothing but the nucleus of helium ( H 2 4 e ). With the emission of an alpha particle ( H 2 4 e ), the atomic number of the radioactive nucleus decreases by two and mass number by four. The nucleus of hydrogen does not contain two protons and two neutrons, and it has less number of electrons than the alpha particle. So it can not emit an alpha particle.

The diagram below shows a magnetic needle kept just below the conductor AB which is kept in the North-South direction. i) In which direction will the needle deflect when the key is closed? ii) Why is the deflection produced? iii) What will be the change in the deflection if the magnetic needle is taken just above the conductor AB? iv) Name one device which works on this principle.

According to the Right-Hand Thumb Rule for the magnetic field, when we hold a current-carrying conductor in the right hand, where the thumb points towards the direction of the current. When we wrap the fingers around the conductor, the fingers point towards the direction of the magnetic field lines. i) In the first case, when the key is closed the current is from B to A. So, as per the right-hand thumb rule just below the conductor, the direction of the magnetic field is towards east. So, due to this needle will deflect towards east. ii) The deflection is produced due to the magnetic field created when current is passed through the wire. iii) In the second case when a magnetic needle is kept just above the conductor when the key is closed the current direction will reverse i.e. from B to A. So, applying right-hand thumb rule just above the conductor, the direction of the magnetic field generated is towards west. So, the needle will deflect towards the West. iv) A device that works on this principle is a magnetic sensor.

Rewrite and complete the following nuclear reaction by filling in the atomic number of Ba and mass number of Kr: U 92 235 + n 0 1 → Ba _ _ _ 144 + Kr 36 _ _ _ + 3 n 0 1 + Energy

For the better understanding of nuclear reaction, a sample of uranium is bombarded with neutrons in an attempt to produce new elements with Z < 92 . It has been observed that lighter elements (lower atomic number) such as Barium ( Z = 56 ) are formed during the reaction and releases heat. U 92 235 + n 0 1 → Ba 56 144 + Kr 36 88 + 3 n 0 1 + Energy

Define nuclear fission.

Nuclear fission is an exothermic reaction process, in which a heavier atom splits into lighter nuclei. This elemental transmutation can be natural spontaneous splitting by radioactive decay, or can actually be stimulated in a lab by achieving necessary conditions (bombarding) with the resulting nuclei tend to have a combined mass which is less than the original. The missing mass is converted into nuclear energy in the nuclear reaction.

Draw a neat labeled diagram of an A.C. generator.

An A.C. generator is a device that converts mechanical energy into electrical energy and produce electricity. It works based on electromagnetic induction.

If 104 g of water at 30 ° C is taken in a calorimeter made of copper of mass 42 g . When a certain mass of ice at 0 ° C is added to it, the final steady temperature of the mixture after the ice has melted, was found to be 10 ° C . Find the mass of ice added. (Specific heat capacity of water = 4 . 2 J g - 1 ° C - 1 , Specific latent heat of fusion of ice = 336 J g - 1 , Specific heat capacity of copper = 0 . 4 J g - 1 ° C - 1 )

Data Given, Mass of water m 1 = 104 g , temperature of water T 1 = 30 ° C , final temperature T 2 = 10 ° C , mass of calorimeter m 2 = 42 g , temperature of ice T 3 = 0 ° C , specific heat capacity of water S w = 4 . 2 J g - 1 ° C - 1 , specific latent heat of fusion of ice L = 336 J g - 1 , specific heat capacity of copper S c = 0 . 4 J g - 1 ° C - 1 . Let the mass of ice added be m = x , According to the principle of calorimetry, total heat energy lost is equal to total heat gain. ⇒ m 1 S w T 1 - T 2 + m 2 S c T 1 - T 2 = mL + mS w T 2 - T 3 By substituting the given values we get, 104 × 4 . 2 × 20 + 42 × 0 . 4 × 20 = 336 x + x 4 . 2 × 10 8736 + 336 = 378 x x = 9072 378 = 24 g . Hence, the mass added is 24 g .

The melting point of naphthalene is 80 ° C and the room temperature is 30 ° C . A sample of liquid naphthalene at 100 ° C is cooled down to the room temperature. Draw a temperature time graph to represent this cooling. In the graph, mark the region which corresponds to the freezing process.

As naphthalene is having melting point at 80 ° C , in this zone due to the latent heat of fusion the temperature remains steady at 79 ° C (Freezing point of napthalene) as the napthalene solidifies as shown by the portion BC of the curve. This happens even though thermal energy is being lost to the surroundings. There is no change in temperature. This is basically Freezing process zone.

Name the material used for making a Calorimeter. Why is a Calorimeter made up of thin sheets of the this material?

The Calorimeter box is made up of Copper. A calorimeter is a device used to measure the quantity of heat transferred to or from an object. Cu is highly malleable, and hence very thin box of small mass can be made. Copper is a good conductor of heat. Calorimetry is the process of measuring the amount of heat released or absorbed during a chemical reaction. A calorimeter box is made up of Copper because (i) Cu has low specific heat capacity, and thus it reaches the equilibrium temperature quickly by absorbing a small amount of heat. (ii) Cu is highly malleable and hence a very thin box of small mass can be made thus decreasing the heat capacity of the box. This makes sure the calorimeter absorbs or liberates a small amount of heat during the heat exchange.

Calorimetry is the study that related with determining the changes in energy of a system by measuring the heat exchanged with the surroundings and by this holding the law of conservation of energy.