Most of these look like dilution questions which follow a general pattern;
<span>Use M1V1 = M2V2 (because moles in a solution stays constant if diluted) </span>
<span>so, the Concentration before * Volume before = Concentration after * Volume after </span>
<span>Using the first question as an example; 0.2*50 = 100 * M2 </span>
<span>Rearranging for M2: 0.1 </span>
<span>Therefore the concentration of the final solution is 0.1 M </span>
<span>we know that to work out pH you must use negative logs to base 10; i.e. -log(0.1) gives you the pH for this solution which is 1</span>
The Yellow River is the most important water resource for the dry north of China, playing an irreplaceable role in economic development, and agriculture. Since 1960 over 14 dams have been constructed on the river for hydroelectric power, which is vital to northern China's infrastructure.
Answer:
a) A satellite is warmed by sunlight.
Explanation:
Heat transfer by radiation mostly involves heat gain or heat loss from the Sun. In this case, Option A is the only option where sunlight is involved so it is the best example of heat transfer by radiation.
Units of measurement are the terms that we use to describe the size of something. You probably know that units include things like seconds, kilograms, meters, and so forth.
Without standard units of measurement, scientists would have a huge problem understanding what other scientists were saying. After all, if I were to refer to a meter as "the length of my leg" and another scientists were to refer to it as "the length of a Saint Bernard dog", we'd have a lot of trouble when it came to do actual science. To avoid this problem, the SI system of units gives us a convenient and, more importantly, standard set of units that we can agree on.