Nguyên tố R là kim loại kiềm, hiđroxit của R chứa 57,5% khối lượng R. a. Xác định R, Cho biết vị trí của R trong BTH ?

b. Tính thể tích dd H2SO4 0,5M cần trung hoà hết 120 g dd ROH 10% trên ?

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

Acamcorder has a power rating of 17 watts. if the output voltage from its battery is 7 volts, what current does it use?units:

Awoman's basketball has a circumference between 28.5 and 29.0 inches and a maximum weight of 20 ounces (two significant figures). what are these specifications in units of centimeters and grams?