Answer: 1. 
increases.
Explanation:
Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.
For the given equation:
If the concentration of 
is increased , according to the Le-Chatlier's principle, the reaction has to shift to right or forward direction. In order to do that the concentration of products has to increase.
Thus the concentration of increases.
The given question is incomplete. The complete question is :
Which of the following Group 17 elements is the least reactive
a) Flourine
b) Chlorine
c) Astatine
d) Iodine
Answer: c) Astatine
Explanation:
Halogen is the name given to Group 17 family with general electronic configuration of 
which have 7 valence electrons and thus easily gain one electron to attain stable configuration.
As we move down the group from flourine to chlorine to bromine to iodine to astatine , the valence shell moves farther from nucleus and thus tendency to accept the electron decreases and thus reactivity also decreases.
Thus Astatine is the least reactive of all.
Every isotope of an element has a different number of neutrons, which means that the atomic property which is different in each isotope of an element is mass number.
Mass number depends on the number of neutrons in an element.
Here are 4 physical Properties of lanthanum
its
soft
malleable
ductile
and silver white colored metal.
Answer:
4.9cm or 4.90cm
Explanation:
Use column method and align the numbers. Make sure you add the decimal point before you write the answer, otherwise the value would be wrong.
