For the first question, salt is soluble while sand is insoluble or not dissolvable in water. The salt should have vanished or melted, but the sand stayed noticeable or visible, making a dark brown solution probably with some sand particles caught on the walls of the container when the boiling water was put in to the mixture of salt and sand. The solubility of a chemical can be disturbed by temperature, and in the case of salt in water, the hot temperature of the boiling water enhanced the salt's capability to melt in it.
For the second question, the melted or dissolved salt should have easily made its way through the filter paper and into the second container, while the undissolved and muddy sand particles is caught on the filter paper. The size of the pores of the filter paper didn’t change. On the contrary, the size of the salt became smaller because it has been dissolved which is also the reason why it was able to go through the filter paper, while the size of the sand may have doubled or even tripled which made it harder to pass through.
Answer :
Explanation :
The aluminium and fluorine react to give ionic compound aluminium fluoride.
Aluminium has 1 valence electrons in their shell and fluorine has 7 valence electrons in their shell.
For the complete octet, both aluminium and fluorine exchange valence electrons to form an ionic compound.
The aluminium donates its three valence electrons to three fluorine atoms and they form one 
and three 
ions.
Electron transfer image is shown below.
Answer:
(b) Both have the same number of valence electrons.
Step-by-step explanation:
We find the most striking chemical similarities between two Main Group elements when they are in the same Group of the Periodic Table.
Elements in the same Group have the same number of valence electrons.
(a) is <em>wrong</em>, because elements in the same group have <em>different masses</em>.
(c) is <em>wrong,</em> because atoms with the same number of protons belong to the s<em>ame element</em>.
(d) is wrong, because elements in the same Group must be in .
<em>different Periods.</em>
Infrared radiation
Explanation:
The type of electromagnetic waves Jeff uses to make his goggles work are the infrared radiations.
Jeff is certainly using a night vision goggle to see in the dark . It senses infrared radiations
- Infrared radiations are part of the electromagnetic spectrum.
- Every hot objects gives off infrared radiations.
- These googles have thermal imaging sensors that detects these radiations.
- Naked eyes cannot see the radiations.
- The heat emitted is a form of radiation called the infrared radiation.
learn more:
Electromagetic radiation brainly.com/question/6818046
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