(Solved): A 10mL volumetric pipet is correctly used to transfer a portion of a 0.2450M sodium chloride sol ...

A $10?\mathrm{mL}$ volumetric pipet is correctly used to transfer a portion of a $0.2450\mathrm{M}$ sodium chloride solution to a beaker. How should the number of moles of sodium chloride that were transferred in this part of the procedure be recorded? $2.5\times 10^{?3}\mathrm{mol}$ $2.45\times 10^{?3}\mathrm{mol}$ $2.450\times 10^{?3}\mathrm{mol}$ $4.90\times 10^{?3}\mathrm{mol}$ None of the above When reading a buret, it is recommended that you use a white card with a dark mark in the center. What should do with this card, and why? The card is placed behind the buret so the center of the black mark is directly behind the liquid meniscus. The white top of the liquid column is easier to see against the black mark. The card is placed under the buret while you're reading the volume. Any leaks will cause the black mark to smear, and you can easily see the problem. The card is placed behind the buret so the top of the black mark is just below the liquid meniscus. The bottom of the liquid meniscus will reflect the black mark and you can see it easily against the white upper part of the card. The card is placed in front of the buret so that the top of the card is directly below the liquid meniscus. The white card edge can be easily moved to match the top of the liquid meniscus, so that the volume can be read. None of the above