从2L 1mol•L-1的NaOH溶液中取100ml，有关这100ml溶液的叙述中错误的是（ ）
A．浓度为0.1mol•L-1
B．浓度为1mol•L-1
C．含4g NaOH
D．含0.1mol NaOH
由于溶液是均匀的，从2L 1mol/L NaOH溶液中取出100ml溶液，这100ml氢氧化钠溶液与原2L 1mol/L NaOH溶液浓度相同为1mol/L．
A、由于溶液是均匀的，取出的100ml氢氧化钠溶液与原2L 1mol/L NaOH溶液浓度相同为1mol/L，故A错误．
B、由于溶液是均匀的，取出的100ml氢氧化钠溶液与原2L 1mol/L NaOH溶液浓度相同为1mol/L，故B正确；
C、取出的100ml氢氧化钠溶液中氢氧化钠的质量为为0.1L×1mol/L×40g/mol=4g，故C正确；
D、取出的100ml氢氧化钠溶液中氢氧化钠的物质的量为0.1L×1mol/L=0.1mol，故D正确；
故选A．
| The sun today is a yellow dwarf star. It is fueled by thermonuclear reactions near its center that convert hydrogen to helium. The sun has existed in its present state for about 4 billion, 600 million years and is thousands of times larger than the Earth. By studying other stars, astronomers can predict what the rest of the sun’s life will be like. About 5 billion years from now, the core of the sun will shrink and become hotter. The surface temperature will fail. The higher temperature of the center will increase the rate of thermonuclear reactions. The outer regions of the sun will expand approximately 35 million miles, about the distance to mercury, which is the closest planet to the sun. The sun will then be a red giant star. Temperatures on the earth will become too hot for life to exist. Once the sun has used up its thermonuclear energy as a red giant, it will begin to shrink. After it shrinks to the size of the earth, it will become a white dwarf star. The sun may throw off huge amounts of gases in violent eruptions called nova explosions as it changes from a red giant to a white dwarf. After billions of years as a white dwarf, the Sun will have used up all its fuel and will have lost its heat. Such a star is called a black dwarf. After the Sun has become a black dwarf, the earth will be dark and cold. If any atmosphere remains there, it will have frozen onto the earth’s surface. |
According to the passage, which of the following best describes the sequence of stages that the sun will probably pass through
A．Yellow dwarf, white dwarf, red giant, black giant.
B．Red giant, white dwarf, red dwarf, nova explosion.
C．Yellow dwarf, red giant, white dwarf, black dwarf.
D．White dwarf, red giant, black dwarf, yellow dwarf.