What is the value of the standard molar enthalpies of formation at 298K of NaCl(s)?

In relation to mechanics of materials, which option correctly defines a stress?

What is the amount of heat absorbed if two litres of an ideal gas at a pressure of 10 atm expands isothermally into a vacuum until its total volume becomes 10 liters?

Consider a circular hollow tube made of steel which is used for supporting a compressive load of 600 kN. The inner diameter of the tube is 90 mm and the outer diameter is 130 mm. What is the compressive stress, if the length of the tube is 1000 mm?

In relation to bending stress, what is the correct value of bending or flexural modulus (Eb), if P is the normal force, L is the beam length, w is the beam width, t is the beam thickness, and y is the deflection at load point?

Which option can be exchanged in a closed system?

The unit of power in S.I. units is

The maximum stress intensity due to a suddenly applied load is x-times the stress intensity produced by the load of the same magnitude applied gradually. The value of x is

When loads are applied proportionately to a frame structure containing its members in one plane, the structure is called

The angle which an inclined plane makes with the horizontal when a body placed on it is about to move down is known as angle of

The force in member U2L2 of the truss shown in below figure, is