1) Three solid iron cubes whose edges measure 5x3x4 cm respectively, are melted down to form a new single solid cube.What is the surface area of this new cube? A) 512 sq.cm B) 216 sq.cm C) 272 sq.cm D) 126 sq.cm Answer: Option BExplanation:Total volume of the 3 smaller solid iron cubes $=5^{3}+3^{3}+4^{3}$=$=216 cm^{3}$ Volume of new bigger cube $=216 cm^{3} \therefore Edge= 6cm$ Surface area of the cube $=6a^{2}$=216 sq.cm
