<h3>Answer:</h3>
The smallest unit which maintains the physical properties of a compound is a <u>Molecule</u>.
<h3>Explanation:</h3>
Option-A, <u><em>Atom</em></u> is incorrect because statement is asking about the physical properties of a compound. Therefore, as compound is made up of two or more, same or different atoms hence, atom can not be the correct answer.
Option-B, <u><em>Element</em></u> is also incorrect because Element can be mono-atomic like He, Ne, Ar <em>e.t.c </em>or a molecules like N₂, O₂, F₂ <em>e.t.c</em> but it can't be a compound because in compound the joining elements are different as all compounds are molecules but all molecules are not compounds.
Option-C, <u><em>Molecule</em></u> is the correct answer because all compounds are molecules unless the atoms forming the compound are different.
Option-D, <em><u>Alloy</u></em> is also incorrect because Alloys are a homogeneous mixture of two or more metals. Hence, they can't be considered as compounds as they can be separated by physical means.
Answer:
about 19 or 20 g
Explanation:
To do this, is neccesary to watch a solubility curve of this compound. This is the only way that you can know how many grams are neccesary to dissolve this compound in 50 mL of water to a given temperature.
Now, if you watched the attached graph, you can see the solubility curve of many compounds in 100 g of water (or 100 mL of water). So, to know how many do you need in 50 mL, it's just the half.
So watching the curve, you can see that at 20 °C, we simply need between 35 g and 40 g. Let's just say we need 38 grams of NH4Cl to be dissolved in 100 mL of water.
So, in 50 mL, it's just the half. So, we only need 19 g or 20 g of NH4Cl at 20 °C, to dissolve this compound in water.
Answer:
Volcanoes absorbed water vapor from the atmosphere and made the planet very dry and difficult to live
on
C- main sequnce
Regulus A is a binary star consisting of a blue-white main sequence star of spectral type B7V, which is orbited by a star of at least 0.3 solar masses, which is probably a white dwarf. The two stars take approximately 40 days to complete an orbit around their common centre of mass.
