1. The problem statement, all variables and given/known data A silicon chip used in an integrated circuit of a computer has a mass of 4.86 mg. How many silicon atoms are present in this chip? 2. Relevant equations no. of moles of element = no. of particles / 6.22 * 10^23 particles No. of moles of a element : mass of element in g / molar mass of element in g/mol 3. Attempt at solution No. of moles in element = 4.86 / 28 = 0.1736 mol no. of moles = 0.1736 * 6.22 * 10^23 particles = 1.079792e23 particles Just want to make sure if the answer is correct . And another question : If 200.0 mL of 10.0 ºC water and 250.0 mL of 40.0 ºC water are added together, what will be the final temperature of the mixed water? (Assume no heat is transferred to or from the surroundings.) We know that: Change in energy of the water = mass * specific heat * change in temp . therefore the energy amount going out of the warm water is equal to the energy amount going into the cool water. Cold Water Hot Water mass * specific heat * change in temp. = mass * specific heat * change in temp. 200 * 4.184 * (40 - x ) = 250 * 4.184 * (x - 10 ) 836.8 *( 40 - x ) = 1046 * (x - 10) 33472 - 836.8x = 1046x - 10460 1882.8x = 43932 x = 23.3 degrees but the answer is wrong :C Please help urgently !