Hòa tan 8 gam NaOH (M= 40) vào nước thành một lít dung dịch ở nhiệt độ 25oC có tỉ khối d=1,08 g/ml. Tính nồng độ mol/l (CM), nồng độ % (C%) dung dịch NaOH trên. b. Tính pH của các dung dịch sau: NaOH 0,2M; HCl 0,05M và CH3COOH có nồng độ 0,6 M. Biết hằng số điện ly của dung dịch CH3COOH là Ka = 1,86.10-5

Asample of the male sex hormone testosterone, c19h28o2, contains 3.88×10^21 atoms of hydrogen.(a) how many atoms of carbon does it contain? (b) how many molecules of testosterone does it contain? (c) how many moles of testosterone does it contain? (d) what is the mass of this sample in grams?

Two nitro no2 groups are chemically bonded to a patch of surface. they can't move to another location on the surface, but they can rotate (see sketch at right). it turns out that the amount of rotational kinetic energy each no2 group can have is required to be a multiple of ε, where =ε×1.010−24 j. in other words, each no2 group could have ε of rotational kinetic energy, or 2ε, or 3ε, and so forth — but it cannot have just any old amount of rotational kinetic energy. suppose the total rotational kinetic energy in this system is initially known to be 32ε. then, some heat is removed from the system, and the total rotational kinetic energy falls to 18ε. calculate the change in entropy. round your answer to 3 significant digits, and be sure it has the correct unit symbol.

Use the periodic table to determine the electron configuration of dysprosium (dy) and americium (am) in noble-gas notation.