ML Aggarwal CBSE Solutions Class 8 Math 2nd Chapter Exponents and Powers Exercise 2.2
(1) (i) 0.0000000000085 = 85×10/1000000000000 = 8.5×10-13
(ii) 0.000000000000942 = 9.42×102/1000000000000000 = 9.42×10-13
(iii) 6020000000000000 = 6.02×102x1013
= 6.02×1015
(iv) 0.00000000837 = 8.37×102/100000000000 = 8.37×10-9
(2) (i) 3.02×10-6 = 302/1000000×102 = 302/108= 0.00000302
(ii) 1.0007×1011 = 1007/10-11x103 = 1007/10-8 = 100700000000
(iii) 5.375×1014 = 5375/10-14x103 = 5375/10-11 = 537500000000000
(iv) 7.579×10-14 = 7579/1014x103 = 7579/107
= 0.00000000000007579
(3) (i) 0.000000000000000000000001673
= 1.673×103/1000000000000000000000000000
= 1.673×103/1027 = 1.673×10-24g
(ii) 0.0016 = 1.6×10/10000 = 1.6×10/104 = 1.6×10-3cm
(iv) 2.2×10/100000000000 = 22×10-9m.
(v) 0.00000000000000000000334
= 3.34×102/100000000000000000000000 = 3.34×102/1023
= 3.34×10-21 tons.
(iii) 0.000003= 3/1000000 = 3×10-6m.
(vi) 1 trillion = 1000,000,000,000 = 1012
(vii) 149, 600, 000, 000m = 1.496×103x108
= 1.496×1011m.
(viii) 300, 000, 000 m/sec = 3×108 m/sec.
(ix) 5970, 000, 000, 000, 000, 000, 000, 000
= 5.97×102x1021 = 5.97×1023 kg.
(x) 1min = 60sec.
1hr = 60min = 60×60 = 3600sec.
1day = 24hr.
Therefore, 1yr = 365day = 24x365hr.
= (24x635x3600) sec
= 31536000 sec.
Therefore, 3yr = 31536000sec x 3
= 94608000 sec.
= 9.4608×104x103
= 9.4608×107 sec.
(xi) We know that –
1 hec = 100000000 cm2
7 hec = 7×100000000 cm2
= 700000000 cm2
= 7.0x10x108
= 7.0×109 cm2 Ans.
(xii) Annual seals = 3 billion 720 million kg.
= 3000000+720000
= 3720000 kg.
= 372×102x10x10x10x10
= 372×106 kg Ans.
(5) We know that –
1lt = 1,000,000mm3
Therefore, 5lt = 5,000,000 mm3
Therefore, the number of blood cells of mm3 = 5.5 ml
Therefore, the number of blood cells 1,000,000 mm3 = 1,000,000×5.5
= 5,5000,00.0
Therefore, the number of blood cells 5,000,000 mm3
= 5,000,000×55,000,00
= 275,000,000,000,000
= 2.75×1012 ml.
(6) Mass of mars = 6.42×1029 kg.
Mass of sun = 1.99×1030 kg.
Therefore, Total mass = (6.42×1029 + (1.99×1030)
= 6.42×1029 + (19.9×10-1x1029)
= (6.42×1029) + (19.9×1029)
= (6.42+19.9) x 1029 = 26.32×1029 kg.
can u do check your progress also bcz mostly sir will give us questions from there?:)