amt7an sec 1

Which of the following represents the closed system as the time passes ?

• The energy remains constant but the mass changes.

• Both the temperature and the mass change.

• The mass remains constant but the energy changes.

• Both the temperature and the mass do not change.

What is the change in enthalpy on dissolving 40 g of NaOH in water to form one liter of solution, knowing that the temperature rised by 10.6°C       

[NaOH = 40 g/mol]

• -0.443 kJ/mol

• -4.4308 kJ/mol

• -44.308 kJ/mol

• -443 kJ/mol

In the opposite figure, on dissolving caustic potash

in water, the reading of thermometer rises.

This means that this process is ………….

• endothermic and H value has a positive sign

• endothermic and H value has a negative sign

• exothermic and H value has a negative sign.                                                                                                                                                        

• exothermic and H value has a positive sign.                                                

When a piece of copper its temperature equals 150°C is thrown in boiling water , heat transfers from copper to water due to the

• Higher thermal energy of water.

• Higher temperature of copper than water.

• Higher thermal energy of copper

• Higher temperature of water than copper.

On adding 50 g of ice whose temperature is 0°C to a calorimeter containing 50 g of water whose temperature is 15°C, the thermometer reading drops,it is concluded that the heat lost by the calorimeter equals……….

• the heat lost by the water.

• the heat gained by the ice.

• the sum of the heat lost by the water and the heat gained by the ice.

• the difference between the heat gained by the ice and the heat lost by the water.

The quantity of heat of 8.36 x 10^-3 kJ is equivalent to……………..

•  0.02 cal

• 0.2 cal

• 2 cal

• 2 x 10^-3 cal

Plant cells use the light energy in photosynthesis process.

Which of the following represents correctly that process ?

• It is an endothermic process / As the heat released during the formation of the bonds in products molecules is less than the heat required

           for breaking the bonds in reactants molecule 

• It is an endothermic process / As the heat released during the formation of the bonds in products molecules is more than the heat required

        for breaking the bonds in reactants molecules.

• It is an exothermic process / As the heat released during the formation of the bonds in products molecules is less than the heat required for breaking the bonds in reactants molecules.

• It is an exothermic process / As the heat released during the formation of thebonds in is more products molecules than the heat required

        for breaking the bonds in reactants molecules.

The following thermal equation represents the combustion reaction of

hexane C ₆H₁₄         

C₆H_14(g) + O_2(g)→ 6CO_2(g) +7H₂O_(L)                     H=-4158 kJ/mol

What is the value of ∆H of the hypothetical reaction :

12CO_2(g) + 14H₂O →2C₆H_14(g) +19O_2(g) ?

• + 8316 kJ

• + 4158 kJ

• -2079 kJ

• -3568 kJ

A cup filled with water is.........

• a closed system.

• an open system

• an isolated system

• an equilibrium system

The egg is an example for the ........

• closed system

• open system

• isolated system

• closed or open system