Question

The Digits Of a Three Positive number are in ap and the sum of digits is 15 on subtracting 594 from the number,the digits are reversed. find the number

Answer 1

in the modern periodic table, groups are the vertical columns.
1)valence electrons:-
across a period- first increases then decreases(12343210)
group- remains same (eg 1st group all alkalis have 1valence electrons)
2)outershells
period -remains same
group-increases by one down the group
3)atomic size
periods -decreases across a period bcuz of increasing nuclear charge that tends to pull electrons closer
group-increases down the group as a new shell is being added
4)metallic character-
periods - decreases across period as the ability to lose electrons decreases (and you can see that metals are concentrated on the left and non metals on the right)
groups - increases down the group as the valence electrons are far apart and thus day to lose
5)effective nuclear charge-
period - increases across the period because protons are being added so more nuclear charge(atomic no. is equal to no. of protons)
groups - I'm not sure of this answer
sorry
but I think the rest answer is correct
hope this is gonna help you out!
student-name Avni Johari answered this
The vertical columns in the periodic table are called groups. An extra shell is added as we go down the group. But the elements have same no of electrons in their respective valence shells, i.e their valency is same and hence they show similar chemical properties.
i) No of valence electrons remains same in a group.
ii) No of shell increases as we go down. An extra shell is added in each step.
iii) Size of atoms increases as we go down due to addition of an extra shell. The attraction between the nucleus and the outermost electron decreases and size increases.
iv) Metallic character increases as the size increases. The tendency to lose electrons increases as the attraction decreases between the nucleus and the outermost electrons.
v) Effective nuclear charge experienced by valence electrons decreases. Effective nuclear charge is the net amount of positive attraction of the protons experienced by the valence electrons. As a new shell is added the inner electrons shield the charge of the protons by reaching the outermost electron and hence the effective nuclear charge experienced by the valence electrons is less.

Answer 2

Let the three digits be
a-d ,a, a+d

The number :
100(a-d)+10(a)+(a+d)

By the given condition
sum of digits is 15.

a-d+a+a+d=15
a+a+a=15
3a=15
a=15/3
a=5

By the given condition.
when 594 is subtracted from the number the digits are reversed.

100(a-d)+10a+(a+d)-594
=100(a+d)+10a+(a-d)

100a-100d+a+d-594
=100a+100d+a-d

so,,
-100d+d-594=100d-d
-100d-100d+d+d=594
-200d+2d=594
-198d=594
d=594/-198
d=-3

so,we have
a=5 & d =-3

Digits:
a-d=5-(-3)=5+3=8
a=5
a+d=5+(-3)=5-3=2

a-d=8, a=5,a+d=2

NUMBER:

100(a-d)+10a+(a+d)
=100(8)+10(5)+(2)
=800+50+2
=852


Therefore,
The three digit number is 852.


hope this helps!!!