1 g of water cools down from its boiling point to its freezing point, it gives off about 420 J of heat energy. By how much does its mass change because of this loss in energy?

Explain why on addition of 1 mol of NaCl to 1 litre of water, the boiling point of water increases, while addition of 1 mol of methyl alcohol to one litre of water decreases its boiling point.

In a hydrogen atom, the electron and proton are bound at a distance of about 0.53 A: (a) Estimate the potential energy of the system in eV, if the zero of potential energy is taken at 1.06 overset @A separation of the electron from proton? (b) What is the minimum work required to free the electron, given that its kinetic energy in the orbit is half the magnitude of potential energy obtained in (a)?

A system 500 j or heat and does work of 50 j on its sourroundings. Calculate the change in internal energy.

Properties such as boiling point, freezing point and vapour pressure of a pure solvent change when solute molecules are added to get a homogeneous solution. These are called colligative properties. Applications of colligative properties are very useful in day-to-day life One of its examples is the use of ethylene glycol and water mixture as an anti-freezing liquid in the radiator of automobiles.A solution M is prepared by mixing ethanol and water. The mole fraction of ethanol in the mixture is 0.9.Given: Freezing point depression constant of water (Kfwater​)=1.86Kkgmol−1Freezing point depression constant of ethanol(Kfethanol​)=2.0Kkgmol−1 Boiling point elevation constant of water(Kbwater​)=0.52Kkgmol−1 Boiling point elevation constant of ethanol (Kbethanol​)=1.2Kkgmol−1 Standard freezing point of water =273K Standard freezing point of ethanol =155.7K Standard boiling point of water =373K Standard boiling point of ethanol =351.5K Vapour pressure of pure water =32.8mmHg Vapour pressure of pure ethanol =40mmHg Molecular weight of water =18gmol−1 Molecular weight of ethanol =46gmol−1 In answering the following questions, consider the solutions to be ideal dilute solutions and solutes to be non-volatile and non-dissociative. Water is added to the solution M such that the mole faraction of water in the solution becomes 0.9. the boiling point of this solution is

A gas expands against a variable pressure given by P = (20)/(V) (where P in atm and V in L). During expansion from volume of 1 litre to 10 litre, the gas undergoes a change in internal energy of 400 J. How much heat is absorbed by the gas during expansion?

A circle is the locus of a point in a plane such that its distance from a fixed point in the plane is constant. Anologously, a sphere is the locus of a point in space such that its distance from a fixed point in space in constant. The fixed point is called the centre and the constant distance is called the radius of the circle/sphere. In anology with the equation of the circle |z-c|=a , the equation of a sphere of radius a is |r-c|=a , where c is the position vector of the centre and r is the position vector of any point on the surface of the sphere. In Cartesian system, the equation of the sphere, with centre at (-g, -f, -h) is x^2+y^2+z^2+2gx+2fy+2hz+c=0 and its radius is sqrt(f^2+g^2+h^2-c) . Q. Equation of the sphere having centre at (3, 6, -4) and touching the plane rcdot(2hat(i)-2hat(j)-hat(k))=10 is (x-3)^2+(y-6)^2+(z+4)^2=k^2 , where k is equal to

Define electric potential energy. Give its units. Calculate electric potential energy of system of n point charges.

100 g of water is supercooled to -10^@C . At this point, due to some disturbance mechanised or otherwise some of its suddenly freeazes to ice What will be the temperature of the resultant mixture and how much mass would freeze? (S_W = 1 cal//g//^@C and L_(W fusion) = 80 cal/g].

Calculate the amount of KCl which must be added to 1 kg of water so that its freezing point is depressed by 2 K.