The correct answer is option (c) 4000

Explanation:

Given that, the dimensions of the godown are 40 m, 25 m and 10 m

Volume = 40 m × 25 m × 10 m = 10000 m3

Given that, volume of each cuboidal box is 2 m × 1.25 m × 1 m = 2.5 m3

Hence, the total number of boxes to be filled in the godown is

= 10000/2.5 = 4000

The correct answer is option (d) None of the above.

Explanation:

We know that, the total surface area of a cylinder is 2p r(h + r), when the radius is “r” and height is “h”.

If the radius is 2r and the height is (1/4)h, then the total surface area becomes,

= 2p (2r) ((1/4)h + 2r)

= 4 pr [(h+8r)/4]

= pr (h+8r)

The correct answer is option (c) Curved surface area of the cylinder will be halved.

Explanation:

We know that the curved surface area of a cylinder with radius “r” and height “h” is given as

The curved surface area of a cylinder = 2prh … (1)

Now, the new curved surface area of cylinder with radius 2r and height (1/4)h, then the new curved surface area is

= 2p(2r)(1/4)h

= prh

Now, multiply an divide the new curved surface area by 2, we will get

= (1/2) (2) prh …. (2)

Now, by comparing (1) and (2), we get:

The new curved surface area of a cylinder is (1/2) times of the original curved surface area of a cylinder.

Total number of a particles used for bombardment = 1 mole

1 mole=6.022×1023 particles

number of a particles deflected at angles greater than 50°(>50°)= 1%

Number of a particles deflected at angles greater than 50° = 100-1 = 99%

The actual number of a particles deflected at angles less than 50°= 99/100 × 6.022 × 1023

=5.96 × 1023

Atomic number of sodium (Z) =11 Mass number of sodium (A) = 23

Number of protons in the nucleus = 11 Number of neutrons in the nucleus =23-11 = 12

Number of electrons = 11

Electronic configuration of Na-atom = 2, 8, 1(K,L,M)

Na+ ion is formed from sodium atom by loss of an electron (present in the outermost shell). Hence,

the electronic configuration is 2, 8(K, L). However, the number of protons and neutrons remains the same.

Postulates of Bohr’s model of an atom are

1. Only certain special orbits known as discrete orbits of electrons are allowed inside the atom.
2. While revolving in discrete orbits the electrons do not radiate energy. These orbits or shells are called energy levels. These orbits or shells are represented by the letters K, L, M, N,… or the numbers, n=1,2,3,4,….

Rutherford’s model could not explain the stability of the atom.

Revolving electrons would lose energy as they are the charged particles and due to acceleration, charged particles would radiate energy.

The orbit of the revolving electron will reduce in size, following a spiral path as shown in the figure and ultimately the electron should fall into the nucleus. In other words, the atom should collapse.