What amount of heat (in kJ) is required to convert 19.1 g of an unknown solid (MM = 83.21 g/mol) at -5.00 °C to a liquid at 52.3 °C? (specific heat capacity of solid = 2.39 J/g･°C; specific heat capacity of liquid = 1.58 J/g･°C; ∆Hfus = 3.72 kJ/mol; normal freezing point, T f = 10.3°C)

why is arctic sea ice important? arctic sea ice keeps the polar regions cool and moderate global climate. sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. as sea ice melts in the summer, it exposes the dark ocean surface.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

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i believe the answer is true.