Measure 10 grams of NaCl and add this to a beaker of 100 ml water. a. Stir the salt with a spoon to dissolve. Record how long it takes to dissolve all of the salt.

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the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.

intermolecular forces are the forces between molecules or particles.

there are two kinds of van der waals forces: weak london dispersion forces and stronger dipole-dipole forces.

in molecule of water there are dipole-dipole forces between negatively charged oxygen from one molecule of water and positively charger hydrogen of another molecule of water.

hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (h), covalently bound to a highly electronegative atom such as flourine (f), oxygen (o) and nitrogen (n) atoms.  

a redox reaction

explanation:

potassium metal is oxidized to potassium ion, and iodine is reduced to iodide ion, and we add (i) and (ii) together to eliminate the electrons.