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which is an example of a physical change?

a) mixing blue and yellow paint to create green paint
b) adding water and yeast to bread dough in order to make it raise.
c) mixing two liquids together in a test tube and the tube becoming warm.
d) adding a piece of chalk containing calcium carbonate to a glass of mild acid causing the formation of a foam of bubbles.

The lattice enthalpy (formation of ionic solid from ions in the gas phase) for agcl(s) is -916 kj/mol and the hydration enthalpy (dissolution of gaseous ions into water) is -850 kj/mol. how much heat (in joules) is involved in forming 1l of saturated agcl solution (1.8 × 10-4 g / 100 ml water) by dissolving agcl(s)? assume solution volume does not change much upon dissolution. the equations are given below. ag+(g) + cl−(g) æ agcl(s)

The ammonia molecule in the diagram has the observed bond orientation because

Why dose heating increase the speed at which a solution dissolved in water