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Ostrovityanka [42]
3 years ago
15

Why doesn't the earth,s shadow get cast onto the moon every month ?

Chemistry
1 answer:
soldi70 [24.7K]3 years ago
8 0
Becuz the sun refelt off the earth and on to the moon.

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Which of the following pairs of elements is most likely to form an ionic bond?
omeli [17]
While the other pairs, sodium and potassium are the metals, nitrogen and iodine, chlorine and bromine, helium and oxygen are the non-metals. They do not form ionic bond. Hence, the correct pairs of elements likely to form ionic compounds are, potassium and sulfur, magnesium and chlorine
5 0
3 years ago
Which of the following are SI units? Select<br> all that apply.
Dimas [21]
<h3>Answer:</h3>

Seconds (s)

Liters (L)

<h3>Explanation:</h3>

SI units relate to the International System of Units. These units are the base, metric units that are most commonly accepted for different measurements.

Common SI Units

The most common SI units are as follows:

  • Length - meter (m)
  • Time - second (s)
  • Mass - kilogram (kg)
  • Amount of substance - mole (mole)
  • Electric current - ampere (A)
  • Temperature - kelvin (K)
  • Volume - liter (L)

*Note that gram (g) is not an SI unit

Each type of measurement will only have 1 SI unit. This is the unit that will be expected for most answers. Sometimes this means converting an answer into a different unit so it is more widely accepted.

Why SI Units are Important

SI units are important for the same reason that the metric system is used. It gives a standardized list of measurements that scientists across the world can use. Also, it makes it easier to compare scientific findings and studies when all of the measurements are given in the same units.

There are times when it is unrealistic to use SI units. For example, when discussing space, using meters will not be realistic due to the size of space. Also, when measuring the mass of small elements, kilograms are too large. But otherwise, SI units should be used.

3 0
1 year ago
What is the molar mass of calcium carbonate (CaCO3) ?
agasfer [191]

Answer: 15.1 grams

Given reaction:

Na2CO3 + Ca(OH)2 → 2NaOH + CaCO3

Mass of Na2CO3 = 20.0 g

Molar mass of Na2CO3 = 105.985 g/mol

# moles of Na2CO3 = 20/105.985 = 0.1887 moles

Based on the reaction stoichiometry: 1 mole of Na2CO3 produces 2 moles of NaOH

# moles of NaOH produced = 0.1887*2 = 0.3774 moles

Molar mass of NaOH = 22.989 + 15.999 + 1.008 = 39.996 g/mol

Mass of NaOH produced = 0.3774*39.996 = 15.09 grams

Explanation:

6 0
3 years ago
Read 2 more answers
Ionic crystals are excellent insulators and can hold a large amount of heat before melting or boiling.
sweet-ann [11.9K]
It is a true fact that ionic crystals are excellent insulators and can hold a large amount of heat before melting or boiling. The correct option among the two options that are given in the question is the first option. Salt is a great example of ionic crystals and we know that it takes a huge amount of time to melt or boil.
7 0
3 years ago
Which type of energy would most likely create the worst environmental disaster from an accident or spill?
rewona [7]

Answer:

nuclear energy

Explanation:

6 0
3 years ago
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