A group of students is investigating whether wheels affect the force of friction. The students push two boxes each with the same force on a table. One box has wheels and the other does not have wheels. The distance traveled by each box is shown. Experimental Observations
Student 1 Student 2 Student 3 Student 4

Distance traveled by box with wheels 24 cm 22 cm 20 cm 23 cm
Distance traveled by box without wheels 12 cm 14 cm 15 cm 13 cm
Which step should the students take next? (3 points)

a
Make a hypothesis

b
Test another variable

c
Analyze the results

d
Share their conclusion

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

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