MATTER

[EugeneJS]

This is a Year 3-4 topic which I came across recently. Please refer to the attached diagram. I feel that there are two possible answers to this Question. Care to comment? 

[Sensei]

The all answers 1,2,3,4 are true statements, but the right answer for your question is 4. Gases can be easily compressed.

Two shapes might have the same volume.

Edited January 28, 2018 by Sensei

[John Cuthber]

To be fair, it's still slightly ambiguous, but yes, the property that lets you push the piston down is that the volume is variable.

In doing so, you also change the shape.

[studiot]

Air has weight is true, but this dos not affect the piston.

Air occupies space is true, but again does not affect the piston.

Air has a shape. so that is not true. Air is a gas so fills its container and takes its shape.

So you are left with the fact that the air is compressible, which means that its volume can be altered, as the correct selection.

 

[Strange]

"Air has no definite volume" is a horrible way of expressing it. If I were taking the test, I would be tempted to say "none of the above because two of them don't make sense".

[Sensei]

I am reading/interpreting "definite shape"/"definite volume" as "fixed shape"/"fixed volume"..

so reverse of them "no definite shape"/"no definite volume" should be understood as "variable shape"/"variable volume".

(it's basic classical physics school question, so change of shape/volume due to temperature, like it could happen with e.g. metals we can omit)

 

Edited January 28, 2018 by Sensei

[Strange]

8 hours ago, Sensei said:

I am reading/interpreting "definite shape"/"definite volume" as "fixed shape"/"fixed volume"..

That makes sense, in this context. 

But, to me, the opposite of "definite shape" is having an undefined shape - rather like the undefined location of an electron.

[studiot]

I think we should consider this question at the level it is obviously aimed at, especially since the OP is looking for homework help.

This level is obviously pre Boyle's Law, where the pupils are just being introduced to the idea of states and properties of matter.

The question should be considered in the light of what is taught at this level. That is what known facts should be employed to answer this question?

I agree that the question is very carelessly worded or poorly translated from another language.

Either way it starts with a real howler.

It start "Ahmad filled the sylinder with some water as shown".

and then shows a diagram with the cylinder not full of water.

IMHO this is a really poor example to set. In Scinece we need greater precision of language than this.

The cylinder is partially full.

 

On to the choices.

 

At this level pupils are introduced to the idea of three states of matter viz solid liquid and gas, where both gases and liquids are fluids.

The distinguishing feature between liquids (water) and gas (air) is that a gas expands to fill its container and therefore takes the shape of its container.

A liquid does not do this and so does not expand and has a free surface.

 

Using these facts, known at that level enable the correct answer to be selected.

 

But I again agree the whole question is poorly worded.

[studiot]

I am posting this here on behalf of the OP who has reached his post limit.

Eugene please rest asured that this limit is only temporary and you will be a fully accredited member soon.

This limit was because we have too many false posters, like so many forums these days.

However your post is just the sort of Science issue this forum exists for.

Quote

EugeneJS

Hi how do I reply back such that those in this thread can view my response?

Thanks for your latest response. Yes, this is a Grade 3 level question and the question is customised to our culture in this part of the world. So pupils here will understand better what is being asked, culturally speaking. Now, coming back to the science of the question, assuming there is no flaw to it, here is my take: when air is compressed, there is certainly a change in it's volume hence it's volume is not definite.we also see a change in it's shape, hence we can also attribute this observation to a change in the shape of the air inside the syringe. Thus, it looks from here that there are two possibilities, option 3 and 4. I wonder if you agree. 

 

On a different note, how do I post all the above such that all in this thread can view at the same time?

It is not clear if you are a student or a teacher?

No there is no flaw, The English is just badly written.

As I said it is intended that 3 of the 4 possibilities can be eliminated, and I have indicated which one I think that is and why your other choice is not a corrrect reason for the ability to pushing the plunger down.

Water can change its shape, as can air. But water is incompressible, air is compressible. That is the distinguishing point.

 

Oh and welcome to the ScienceForums.

 

Edited January 29, 2018 by studiot

[EugeneJS]

Thanks for making me feel welcomes, Studiot.

When I choose option 3, it is because it works. Air needs to change its shape in order to accommodate a smaller volume in the syringe. That said, it is also true that air is needs to change its volume in order to bring about the same effect. Thus, as I see it there are two possible answers. This makes this question a rather poorly written one. 

I am still open to others who wish to share their two cents worth. 

On 1/29/2018 at 3:39 AM, Sensei said:

The all answers 1,2,3,4 are true statements, but the right answer for your question is 4. Gases can be easily compressed.

Two shapes might have the same volume.

 

Edited January 31, 2018 by EugeneJS

[Raider5678]

Two things previous to this that I feel like the student should know is the concept of heat being energy and the state of being having a reflection of thermal energy levels in the matter.

A cold object has less thermal energy, a hot object has more thermal energy.

This thermal energy is expressed in the matter by its molecules moving around. 

 

However, this is just relative energy in comparison to the other states of matter.

Obviously, some matter is liquid at 32 degrees and others are gas.

So:

 

Matter typically exists in 3 different states, there are exceptions but for 3rd grade, this isn't required to be known in my opinion:

Solid - Lower thermal energy than liquid state

Liquid - Lower thermal energy than gaseous state

Gas - Higher thermal energy than liquid and solid states.

 

As you can see from the diagram, a solid's molecules are "still*"  They have less thermal energy in them making them move, so they're "still".

The liquids state has more thermal energy than the solid state. This thermal energy is expressed by the molecules moving around more, making the matter a liquid.

The gaseous state has the most thermal energy. This thermal energy is translated to the molecules, and they move much faster relative to each other in comparison to the liquid, making them a gas.

 

Since the gaseous state has the most space between atoms due to its state, it can be compressed much easier than a solid or a liquid.

This will help indicate to the student which answer is the correct one because the air will compress before the water** does.

Because I'm assuming the purpose of this is so the student understands states of matter.

 

*still is relative. They can move, but relative to each other they're more still then if it were in a liquid state or a gaseous state.

** Water is also a complicated molecule. It expands as a solid rather than getting smaller like most types of matter. This is because of........... reasons.

[EugeneJS]

Thanks though for taking much time n effort to illustrate. However, I feel that this still doesn't address the Crux of the issue. Feel free to comment further should there be further relevant updates. Stay sane!

[Raider5678]

12 hours ago, EugeneJS said:

Thanks though for taking much time n effort to illustrate. However, I feel that this still doesn't address the Crux of the issue. Feel free to comment further should there be further relevant updates. Stay sane!

Another possibility, if you feel the teaching is okay but not the question, is to take the question, rewrite it in a more efficient/understandable format, and present it to the people who could give you permission to change the test for your students.

 

Since this is a grade 3-4 question as you said, I'm assuming your the teacher, not the student.

Another possibility is you're a parent of a child who was given this question and you feel it's unsatisfactory.

Which one is it, out of curiosity?

 

[studiot]

10 minutes ago, Raider5678 said:

Another possibility, if you feel the teaching is okay but not the question, is to take the question, rewrite it in a more efficient/understandable format, and present it to the people who could give you permission to change the test for your students.

 

Since this is a grade 3-4 question as you said, I'm assuming your the teacher, not the student.

Another possibility is you're a parent of a child who was given this question and you feel it's unsatisfactory.

Which one is it, out of curiosity?

 

+1 Two good replies.

Edited February 1, 2018 by studiot

[EugeneJS]

Thank you for your feedback. I am a science 

17 minutes ago, Raider5678 said:

Another possibility, if you feel the teaching is okay but not the question, is to take the question, rewrite it in a more efficient/understandable format, and present it to the people who could give you permission to change the test for your students.

 

Since this is a grade 3-4 question as you said, I'm assuming your the teacher, not the student.

Another possibility is you're a parent of a child who was given this question and you feel it's unsatisfactory.

Which one is it, out of curiosity?

 

I am a Science educationist , having taught Year 3s all the way to Year 10 in fields like Chemistry, Biology and Physics. I take a strong interest in science matters. The question I have here is one taken from the national exam which was conducted recently in September 2017. It was only recently released to the public. That's when I chanced upon it. 

It is therefore very crucial that I fully understand first and foremost the question in its entirety before I pass them on to my pupils. Then I will be fully prepared for their questions. I will also like to garner feedback from forums such as this to get a better understanding of the range of responses that are possible. Only when I feel I have fully understood the question and answer, will I be able to better explain these questions to my students. 

So in your opinion, you feel the question can be improved further? Cause I have argued earlier that the answers seem to fit options 3 and 4.