Question

Do tree pa bird badhe h......... Ek bird kahte h agr tum mujhe 1 bird dedo to ma tumhare double ho jao gi........ Wahi dusri bird kaahte h ki agr tum mujhe ek bird dedo to ma tumhare barabar ho jao..........dono tree ma kitni bird ha?

Answer 1

Suppose that bird A has x birds and bird B has y birds.
  A/Q,  x+1= 2(y-1)  ⇒ x - 2y = -3    -----------(i)
  and,   y+1 = x-1 x- y = 2      -------------(ii)
Subtracting Eqn(i) - Eqn(ii)
  -2y + y = - 3-2y = 5  Put the value of y in Eqn(ii)  x = 2+ 5 = 7   Hence Bird A has 7 birds and Bird B has 5 birds.

Answer 2

(a) Magnesium chloride →MgCl2 (b) Calcium oxide →CaO (c) Copper nitrate →Cu(NO3)2 (d) Aluminium chloride →AlCl3 (e) Calcium carbonate →CaCO3

6.022×1023 102

× 0.051 molecules

= 3.011 × 1020 molecules of Al2O3 The number of aluminium ions (Al3+) present in one molecules of aluminium oxide is 2. Therefore, The number of aluminium ions (Al3+) present in 3.11 × 1020 molecules (0.051g) of aluminium oxide (Al2O3) = 2 × 3.011 × 1020 = 6.022 × 1020 1 mole of aluminium oxide (Al2O3) = 2 × 27 + 3 × 16 = 102g i.e., 102g of Al2O3 = 6.022 × 1023 molecules of Al2O3 Then, 0.051 g of Al2O3 contains =