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3 years ago

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Your mom is playing the drums in the basement. Whenever she hits the drum with all her force, the box next to the drums shakes,

rattles and almost rolls. What is occurring? A frequency B diffraction C resonance D interference

1 answer:

snow_tiger [21]3 years ago

3 0

It’s “a”, frequency because the sound waves will cause vibrations in object close by

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Which of these is a chemical property?

ankoles [38]

Answer:

The second choice, or flammability.

Explanation:

The flammability of something is how easy it is for it to burn or ignite.

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3 years ago

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1. Sometimes scientists need to be able to replicate the results of a scientific experiment. Explain in what situation(s) this w

Andrej [43]

I need this also I’m just here for points

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2 years ago

Which of the following is an indication of a physical change?

blagie [28]

I would like to say c

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An unknown compound contains 38.7 % calcium, 19.9 % phosphorus and 41.2 % oxygen. what is the empirical formula of this compound

Softa [21]

Answer: Ca3(PO4)2

Explanation:

We assume that the sample is 100.0 g.

The sample contains 38.7 g of Ca, 19.9 g of P, and 41.2 g of O as the proportions show.

Then we can calculate the number of moles of each component (n = m/atomic mass).

The number of moles of Ca = 38.7/40.078 = 0.96 mol.

The number of moles of P = 19.9/30.97 = 0.64 mol.

The number of moles of O = 41.2/15.99 = 2.75 mol.

Now, we can get the molar ratios of different components (Ca, P, and O) in the sample by dividing the number of moles of each component by the lower number of moles, that we should divide the number of moles by (0.64).

Ca: P: O = (0.96/0.64) : (0.64/0.64) : (2.75/0.64) = 1.5 : 1 : 4.

To avoid the fraction of the ratios, we can multiply all ratios by 2.0.

Now, the ratio of Ca : P : O will be 3 : 2 : 8.

That main the empirical formula of the compound is Ca3P2O8 which can be expressed as calcium phosphate (Ca3(PO4)2).

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2 years ago

These elements belong to different Physical and chemical properties , which means they have different and different . Sodium is

Finger [1]

Answer:

Check explanation section.

Explanation:

Yes, that is true. Sodium with chemical symbol Na belongs to the group 1 on the periodic table. Group 1 elements are known as Alkali metals. Other elements in the group are Caesium, lithium, Rubidium, francium and potassium.

Neon belongs to the noble gas of group 8/0.

Sodium is very reactive and and good conductor of electricity. Sodium reacts with water for the production of hydrogen (NB: this reaction is vigorous).

2Na(s) + 2H2O ------------> 2NaOH + H2(g).

They can react with nonmetals such as the halogens. For instance;

Na + Cl2 -------------------------------> 2NaCl.

Sodium is ductile and have low melting point( but high compared to neon).

Neon is not active chemically and it has no odour and no color

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2 years ago