Answer:
с
Explanation:
the first quantum number of an electron gives the information about the energy level the electron is in
Complete question is;
Chemical reactivity of alkali metals increases down the group while reactivity of halogens decreases down the group. Give reasons
Answer:
Explained below
Explanation:
Alkali metals exhibit reactivity due to their electropositivity. Now, for alkalis, their electro-positivity increases down their group. Since their reactivity increases with increase in electropositivity, it means their reactivity also increases down the group.
Whereas, the reactivity of halogens occurs as a result of their electronegativity. Now, electronegativity for halogens decreases down the group. Since their reactivity decreases with decrease in electronegativity, it means that their reactivity will also decrease down the group.
<u>Answer:</u>
A reaction is said to occur if there is a formation of an insoluble solid or a precipitate(s) or a liquid (l) or a gas(g).
If both the reactants and products are in aqueous state, No reaction takes place.

All chlorides and Bromides are soluble except that of Ag, Hg and Pb.
Hence, No reaction takes place since all the reactants and products are in aqueous states.

Salts of Group IA are soluble. Hence No reaction takes place

(REACTION TAKES PLACE)
All hydroxides are insoluble except that of Group IA, ammonium ion and Group IIA down from Calcium.
Hence Reaction takes place with the formation of
precipitate
The patch area in square kilometers is 1.59*10⁻⁹ km₂
Why?
This is an unit conversion problem. We have to convert from cm² to km². We can do that by knowing that there are 100 cm in 1 m, and 1000 m in 1 km, so 100000 cm=1km. Knowing that we can apply the following conversion factor:

Now to convert this value to scientific notation, we have to move the decimal point to the right until we get a whole number, and the exponent of the number 10 is going to be the number of spaces we moved to the right (negative), so the final answer is:

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