Structural Formulas for Covalent Molecules Is anyone good at doing these because I am so confused

1) C2H4

2) C3Cl8

3) SCl2

4) HClO2

5) HNO2

6) H2SeO3

7) H2S2

8) C2H6O2

9) C2H7N

10) C2NH3

11) C2PSH3

12) CH2O2PN

13) C2H2S

14) CH2O

15) N2H2

Measuring which physical property is most likely to produce the most precise results when trying to identify a substance

Microtubular fibers that assist in the movement of chromosomes during nuclear division in conjunction with proteins, makes up the small and large organelle pieces that assemble prior to translation three-base nucleotide sequence that can complementarily pair with the functional transcript, allowing a particular material to be brought to a ribosome particular time in the cell cycle when the cell’s systems determine if the cellular conditions are appropriate to continue through the cycle time in the cell’s cycle when proteins are made and organelles are duplicated enzyme that allows proper nucleotide bonding during transcription specific dna sequence which will initiate gene transcription division of the cell’s cytoplasm specific bond that forms between two amino acids when a carboxyl group binds to a amino group three-base sequence that does not code for a particular amino acid a paired organelle which facilitates the formation of movement microtubules time in the cell’s cycle when the microtubular structures exert an equal pressure on the cell’s genetic material

Suppose a lab group reports a ppercent yield of sand of 105. is it really possible to collect more sand than was originally represented? what is the possible explanation for the extra product?