Identify effective techniques for accurate pipet use. Select all that apply. Select one or more: Measure liquid by aligning the meniscus with the volume line. Leave any air bubbles in a pipet that occur after drawing up liquid. Do not let liquid enter the pipet bulb or pump. Use the pipet bulb to force the last drop out of the tip.

Measure liquid by aligning the meniscus with the volume line.

Explanation:

A pipette is an instrument specially made for measuring a small volume of liquid.

The pipette comes in various sizes to be used in measuring various volumes of liquid. Generally, the pipette has a volume line which helps us to measure a liquid.

A liquid is measured by aligning the meniscus with the volume line.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

b.

the accuracy of the data.