What is the balanced chemical equation for the reaction of element A (unshaded s
ID: 1018570 • Letter: W
Question
What is the balanced chemical equation for the reaction of element A (unshaded spheres) with element B (shaded spheres) as represented below?
3.
Which of thes ions is the smallest?
Which of thes ions is the smallest?
Cl-
49.
Which of the following decay processes give a product nuclide whose atomic number is one less than the starting nuclide?
Which of the following decay processes give a product nuclide whose atomic number is one less than the starting nuclide?
K+ Se2- Ca2+Cl-
49.
Which of the following decay processes give a product nuclide whose atomic number is one less than the starting nuclide?
Which of the following decay processes give a product nuclide whose atomic number is one less than the starting nuclide?
beta decay and positron decay positron decay and electron capture gamma decay and beta decay alpha decayExplanation / Answer
Solution:- (1) As per the given information, unshaded spheres represents element A and shaded spheres represents element B. By looking at the diagram A is monoatomic and there are 4 atoms of it, so it would be written as 4A. B is diatomic and there are 6 molecules of B and it will be written as 6B2. On product side one atom of A is bonded to three atoms of B so the product is written as AB3. There are 4 molecules of AB3 so it could be written as 4AB3. The balanced equation is written as...
4A + 6B2 --------> 4AB3
(2) For the given orbital filling diagram the given notation is shorthand notation. [Ar] represents 18 electrons since atomic number of Ar is 18. After this we have 2 electrons in 4s, 10 electrons in 3d and 3 electrons in 4p. So, total electrons that is atomic number of the element is 18 + 2 + 10 + 3 = 33
Also, the p subshell is incomplete and has only three electrons in it. It's an indication for a p- block element and this block elements are placed on right side of the periodic table from group number 13th to 17th. If we take a look at A, B, C and D then it is C present in p-block (15th group). So, the correct element is is indicated by C.
It is also confirmed if we take a look at periodic table for the element with atomic number 33. It is As(Arsenic), a p-block element with atomic number 33 present in 15th group.
(3) Atomic radius decreases left to right and increases top to bottom in periodic table. cation has smaller size as compared to its neutral atom and anion has bigger size as compared to its neutral atom.
Now if we take a look at the given ions then K and Ca are the elements of same period. Ca is right to K and also the charge on Ca is greater than K, so the size of Ca2+ is smaller than K+. Cl is above Se as Cl is in 3rd period where as Se is in 4th period. Both of these have negative charge so no doubt their size is bigger than Ca2+ and K+. Se is below Cl and also the charge on Se is more negative(-2 unit), so the size of Se2- is bigger than the size of Cl-.
So, the smallest ion is Ca2+ and biggest ion is Se2-.
(49) It would not be alpha decay since in alpha decay the atomic number of product nuclide is two less than starting nuclide and mass number is 4 less than starting nuclide.
In beta decay, atomic number of product nuclide is one greater than its starting nuclide where as in positron decay it is just opposite means atomic number decreases by one unit. So, it is not the correct choice since one increases and other decreases the atomic number by one unit.
In positron decay as well as electron capture equations the atomic number is decreased by one unit so this one is looks good as both of these decreases the atomic number by one unit and that is what we want.
Gamma radiation does not change atomic number as well as mass number means. Beta decay increases the atomic number by one unit. this one is also not correct since they want a decrease in atomic number by one unit.
So, only second choice "positron decay and electron capture" is good.
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