Potassium has 20 neutrons
Hope this helps
Answer:
Wide melting point range - impure sample with multiple compounds
Experimental melting point is close to literature value - pure sample of a single compound
Experimental melting point is below literature value - impure sample with multiple compounds
Narrow melting point range - pure sample of a single compound
Explanation:
The melting point of substances are easily obtainable from literature such as the CRC Handbook of Physics and Chemistry.
A single pure substance is always observed to melt within a narrow temperature range. This melting temperature is always very close to the melting point recorded in literature for the pure compound.
However, an impure sample with multiple compounds will melt over a wide temperature range. We also have to recall that impurities lower the melting point of a pure substance. Hence, the experimental melting point of an impure sample with multiple compounds is always below the literature value.
To measure the mass of a given powdered substance do the following:
1. Zero the weighing balance, that is, put the weigh balance at zero mark.
2. Put an empty weighing paper on the balance and take its reading. Record it as X1.
3. Use spatula to put the powder you want to measure on the weighing paper on the balance. Take your reading and record it as X2.
The mass of the powered is X2 - X1.
Answer:
both plant and animal cells must break down food molecules to get energy from them
