2. Which one of the following statements concerning U2+(238U ) is incorreet: a)Themassnumberisequatto238.b)Thenumberofelectronsisequalto90b)Thenumberofprotonsisequalto90d)Thenumberofneutronsisequal146 3. Rhenium ( Re ) has two isotopes: thiRe and 16R e with an average atomic mass of 186.21 amu. Rhenium is 70.4% Wre which has a mass of 186.956 amu. The mass or 185R Re in amu is equal to: a)185.76b)187.00c)185.31d)184.44 4. The mass percent of nitrogen in CsH4N4O2 is equal to: a) 8.24 b) 16.50 c) 28.87 d) 49.50 5. A compound contains only C,H, and N. Combustion of 80.6g of the compound produces 67.0g CO2 and 82.2gH2O. The empirical formula of this compound is: a) CHN b) CH2 c)C3H18N6d)C2H12N3 6. Which of the following is (are) a metal: Li,O2,NeI,I,Pt,Se,Sr a)Li,andPtonlyb)Li,PtandSronlyc)O2,I2andNeonlyd)O2,I2,SeandNeonly 7. The work done when a gas expands at constant temperuture from 20.2mL to 90.3mL at a a) 0.78J b) 0.42J c) 42.6J d) 78.1J