Science 8th grade questions? PLEASE HELP?

Question

Question 18 (Multiple Choice Worth 4 points)

Elements in the same column of the periodic table share

similar properties.

the same number of protons.

similar masses.

the same number of electrons.



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Question 19 (Multiple Choice Worth 4 points)

Oxygen, sodium, and boron are examples of what type of matter?

Compound

Heterogeneous Mixture

Element

Solution



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Question 20 (Multiple Choice Worth 4 points)

Which of the following is not an acid?

HCl

H2SO4

HNO3

NaOH



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Question 21 (Multiple Choice Worth 4 points)

Something that can be observed, measured, or changed without altering the identity of a substance is called a(n) ____ property.

physical

observable

chemical

changeable



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Question 22 (Essay Worth 4 points)

If an object has a volume of 2 milliliters and a mass of 10 grams, calculate the density of the object.






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Question 23 (Essay Worth 4 points)

If a neutral atom has a mass of 15 amu and an atomic number of 7, determine the number of protons, neutrons, and electrons in the atom.

NO RUDE ANSWERS PLEASE ! Thanks !

Answer 1

18, similar properties.

19, element

20, NaOH

21, physical

22, density = 10g / 2ml = 5g/ml

23, 7protons, 7 electrons, 8 neutrons

Answer 2

In line with your approaches part: you might be measuring rainfall accumulation, now not price, a expense is rainfall accumulation divided by means of time. Assuming you might be measuring a cost... One supply of error comes from the instrument itself. Each and every rain gauge is percise to a certain quantity. And that designated amount is area to human error, if it's a easy contianer with marked off numbers to the facet. There are a kind of rain gauge, each and every with thier execs and cons quite often a rain gauge supply ____ readings if = _____ too excessive = in the event you don't dry the gauge, and excess water is left on the gauge too low = the time it takes to file how much water accumulated. If an excessive amount of time elapses, you loose water through evaprotation.

Answer 3

do it yourself idiota