The atomic radius of main group elements generally increases down a group because as there are more electrons they are farther away from the nucleus and the electrons closer to the nucleus shield the outer electrons from the protons for attraction.
Answer:
B. Libra
Explanation:
Libra's range from September 23rd to October 22nd
The hydrogen deficiency index( HDI) of strigol is = 10
<h3>How to calculate HDI:</h3>
The hydrogen deficiency index is used to measure the number of degree of unsaturation of an organic compound.
Strigol is an example of an organic compound because it contains carbons and hydrogen.
To calculate the HDI using the molecular formula given (C19H20O6) the formula for HDI is used which is:

where C = number of carbon atoms = 19
n= number of nitrogen atoms = 0
h= number of hydrogen atoms = 20
X = number of halogen atoms = 0
Note that oxygen was not considered because it forms two bonds and has no impact.
There for HDI =

HDI=

HDI =

HDI = 10
Therefore, the hydrogen deficiency index of strigol is = 10
Learn more about unsaturated compounds here:
brainly.com/question/490531
The two ways to make a saturated solution are 1 reducing the temperature of the solution and Adding more solute.<span> </span>
Answer:
OPTION (A) : Testing a rock sample for gold content
Explanation:
For testing a rock sample of gold content you will need a Chemist. To test the material, the sample is rubbed on black stone which will leave a mark on the stone. This mark is tested by applying aqua fortis i.e nitric acid on the mark. If the mark gets dissolve then the material is not gold. If the mark sustain the it is further tested by applying aqua regia i.e nitric acid and hydrochloric acid which will prove the sample is of gold if it gets dissolve on using hydrochloric acid. The purity of the sample can be checked by differing the concentration of the aqua regia and comparing it with the gold material of the known purity.