white phosphorus is used in flares and explosives, so may be important in warfare, etc. Red phosphorus is used in matches (side of matches) and in fertilizers which are essential to growing plants. I don't know if that is economically important, but there are many ways that phosphorus benifit the economy. One downside on the economy is that phosphorus is one of the main ingredients in meth, which of course causes trouble for the economy ( law enforcement, medical, etc. )
Answer:
Option-B (Carbon and Silicon)
Explanation:
Among the given pairs only carbon and silicon have the most similar properties. This is because,
Sodium and Magnesium belong to different groups. Sodium present in Group I has one electron in its valence shell and capable of transferring only one electron while, Magnesium present in Group II have two electrons in its valence shell and is capable of donating two electrons. Hence, both show different properties.
Example:
2 Na + Cl₂ → NaCl
Mg + Cl₂ → MgCl₂
As shown in reactions when Sodium and Magnesium are treated with Cl₂ they give a products with different proportions.
Carbon and Silicon show almost same properties because both belong to Group IV hence both are capable of forming four bonds. Also, they share the same property of self linkage in making a long chains.
Argon and Chlorine also belong to two different groups. Argon is present in Group VIII (Noble Gases) and Chlorine is present in Group VII (Halogens). Hence, Argon is an inert specie which is non reactive while Chlorine gives different reaction easily.
Potassium and Calcium belong to different groups. Potassium present in Group I has one electron in its valence shell and capable of transferring only one electron while, Calcium present in Group II have two electrons in its valence shell and is capable of donating two electrons. Hence, both show different properties.
Example:
2 K + Cl₂ → KCl
Ca + Cl₂ → CaCl₂
As shown in reactions when Potassium and Calcium are treated with Cl₂ they give a products with different proportions.
Answer: 116 g of copper
Explanation:
where Q= quantity of electricity in coloumbs
I = current in amperes = 24.5A
t= time in seconds = 4.00 hr = 
(1hr=3600s)
of electricity deposits 63.5 g of copper.
352800 C of electricity deposits = 
of copper.
Thus 116 g of Cu(s) is electroplated by running 24.5A of current
Thus remaining in solution = (0.1-0.003)=0.097moles
The answer is visible rays. For example, when a rain storm stops, the sun comes out and you are likely to see a rainbow. This is because the sun shines on water molecules in the air and the colors appear. These colors are called visible light. The only ray that a naked Human eye can see
Stearic acid is <span>a solid saturated fatty acid obtained from animal or vegetable fats.</span>
