Questions for Chem and Bio

[Snow Leopard]

Hey,
I did Biology and Chemistry as electives.
I got a few questions wrong but neither of my teachers wrote the answer I was meant to have for the q's I got wrong.

For Biology:
-When a cell of multicellular organism was viewed under a light microscope, a cell wall and nucleus were visible. The cell could be from a:
My answer: plant only

- Cellular agens capable of causing infection of body cells include:
My answer: prions

- HIV attacks immune cells and in particular:
My answer: Killer T cells

For Chemistry:
- The element that belongs to group 4 and period 5 is:
My answer: Zicronium

- 2Mg(s) + O₂ → 2MgO(s)
The above equation is what type of reaction
My answer: Synthesis

- Complete the equation: acid + metal hydroxide → salt +_________
My answer: Oxygen

- A question to do with the dot structure of carbon dioxide
My answer: This was a M.C and we had to choose a picture so yeah.

- Which of the following is not an ionic compound?
My answer: NaCl
The other options were:
CO₂
CaCl₂
AgNO₃

- When a metal reacts  with hydrochloric acid, the products are:
My answer: A salt and oxygen gas

- Which of the following processes is an example of a chemical reaction?
My answer: Iron rusts in a damp environment
The other options:
A mist forms when you breathe out onto cold glass
Ice melts as you hold it in the palm of your hand
A litre of water boils dry in a saucepan

- The calcium atom loses 2 electrons to form an ion.
a) Write the symbol for the ion formed.
My answer: Ca^-2
b) How many electrons does the calcium atom have in its outer shell?
My answer: 4 electrons

- A scientist takes a piece of calcium metal and heats it in the presence of oxygen gas to produce solid calcium oxide.
Consider the reaction types: combination, decomposition, precipitation, combustion, neutralisation and displacement. Which 2 types apply to the reaction above?
My answer: Combination (correct) and precipitation (incorrect)

Sorry for the long post and if anyone could give insight as to why my answers were wrong and I'd really apreciate it. 

[^^^111^^^]

Hey,
I did Biology and Chemistry as electives.
I got a few questions wrong but neither of my teachers wrote the answer I was meant to have for the q's I got wrong.

For Biology:
-When a cell of multicellular organism was viewed under a light microscope, a cell wall and nucleus were visible. The cell could be from a:
My answer: plant only

- Cellular agens capable of causing infection of body cells include:
My answer: prions

- HIV attacks immune cells and in particular:
My answer: Killer T cells

For Chemistry:
- The element that belongs to group 4 and period 5 is:
My answer: Zicronium

- 2Mg(s) + O₂ → 2MgO(s)
The above equation is what type of reaction
My answer: Synthesis

- Complete the equation: acid + metal hydroxide → salt +_________
My answer: Oxygen

- A question to do with the dot structure of carbon dioxide
My answer: This was a M.C and we had to choose a picture so yeah.

- Which of the following is not an ionic compound?
My answer: NaCl
The other options were:
CO₂
CaCl₂
AgNO₃

- When a metal reacts  with hydrochloric acid, the products are:
My answer: A salt and oxygen gas

- Which of the following processes is an example of a chemical reaction?
My answer: Iron rusts in a damp environment
The other options:
A mist forms when you breathe out onto cold glass
Ice melts as you hold it in the palm of your hand
A litre of water boils dry in a saucepan

- The calcium atom loses 2 electrons to form an ion.
a) Write the symbol for the ion formed.
My answer: Ca^-2
b) How many electrons does the calcium atom have in its outer shell?
My answer: 4 electrons

- A scientist takes a piece of calcium metal and heats it in the presence of oxygen gas to produce solid calcium oxide.
Consider the reaction types: combination, decomposition, precipitation, combustion, neutralisation and displacement. Which 2 types apply to the reaction above?
My answer: Combination (correct) and precipitation (incorrect)

Sorry for the long post and if anyone could give insight as to why my answers were wrong and I'd really apreciate it. 

Biology:

1. While a plant can have a cell wall and a nucleus, other multicellular organisms with a cell with cell wall and nucleus are fungi and Protoctista (e.g. algae and protozoans) Note: fungi and protoctista do not necessarily have to be multicellular.

2. I think that your answer to this would be wrong, because prions are non-cellular pathogens. Cellular pathogens that can cause infection include fungi and worms/arthropods.

Chemistry:
3. Actually, the word equation would be acid + metal hydroxide -> salt + water. I see where you are getting the oxygen from, but the way I remember this is because metal hydroxide contains both hydrogen and oxygen, which gives water (kind of stupid imo  but yeah).

4. NaCl (aka table salt) is an ionic compound because there are no free electrons. Here Na (sodium) is a cation and Cl (Chlorine) is an anion. On the other hand, carbon dioxide would be a covalent bond because electrons are shared between them. (Out of curiosity have u done these yet? I can explain more in case you haven't).

5. The word equation is as follows: metal + acid -> salt + hydrogen ( usually a gas). Given this info, we can know find the salt for your question. It would be a metal chloride + hydrogen (g). I found the chloride as hydrochloric acid is made of hydrogen and chlorine.

6. For this b is right but A would be wrong. When an atom loses electrons, it will become a cation (positively charged atom) and vice versa for an anion (negatively charged atom). Also try writing as Ca²⁺ instead of Ca^2-.

7. During a precipitation reaction, a precipitate should form. A precipitate is really just a solid that has been deposited. (In case you were wondering, the supernate refers to the liquid). While a solid has formed in this reaction, it has not been depositied. It is a displacement reaction as a reactant has replaced another reactant. Technically speaking, it would be called a single displacement reaction since only one element has replaced another.

Do you have any other doubts?

[Snow Leopard]

Biology:
2. This was a M.C questiona and the other options  were:
- toxins
- DNA virusess
-Gram-negative bacteria
Which do you think it is?

- HIV attacks immune cells and in particular:
My answer: Killer T cells

Does anyone know what I should've written for this q?

Chemistry:

4.(Out of curiosity have u done these yet? I can explain more in case you haven't).

Yeah, we did cover this but I feel like I say everything is a covalent bond even if it's an ionic bond etc. Any tips?

6. Fr othis b is right but A would be wrong. When an atom loses electrons, it will become a cation (positively charged atom) and vice versa for an anion (negatively charged atom). Also try writing as Ca²⁺ instead of Ca^2-.

But, since it looses 2 electrons wouldn't that mean it'd have 8 electrons in its outer shell, therefore making my answer wrong for b.

7. (in case you were wondering, the supernate refers to the liquid).

What is a supernate? Also, I'm still kinda  confused for q .7 cause I don't really get displacement reactions.

Quuestions that I still don't get:
- The element that belongs to group 4 and period 5 is:
My answer: Zicronium

 - 2Mg(s) + O2 → 2MgO(s)
The above equation is what type of reaction
My answer: Synthesis

- When a metal reacts  with hydrochloric acid, the products are:
My answer: A salt and oxygen gas

- Which of the following processes is an example of a chemical reaction?
My answer: Iron rusts in a damp environment
The other options:
A mist forms when you breathe out onto cold glass
Ice melts as you hold it in the palm of your hand
A litre of water boils dry in a saucepan

[^^^111^^^]

Biology:
2. This was a M.C questiona and the other options  were:
- toxins
- DNA virusess
-Gram-negative bacteria
Which do you think it is?
Does anyone know what I should've written for this q?

Chemistry: Yeah, we did cover this but I feel like I say everything is a covalent bond even if it's an ionic bond etc. Any tips?
But, since it looses 2 electrons wouldn't that mean it'd have 8 electrons in its outer shell, therefore making my answer wrong for b.
What is a supernate? Also, I'm still kinda  confused for q .7 cause I don't really get displacement reactions.

Quuestions that I still don't get:
- The element that belongs to group 4 and period 5 is:
My answer: Zicronium

 - 2Mg(s) + O2 → 2MgO(s)
The above equation is what type of reaction
My answer: Synthesis

- When a metal reacts  with hydrochloric acid, the products are:
My answer: A salt and oxygen gas

- Which of the following processes is an example of a chemical reaction?
My answer: Iron rusts in a damp environment
The other options:
A mist forms when you breathe out onto cold glass
Ice melts as you hold it in the palm of your hand
A litre of water boils dry in a saucepan

Sorry, I just realised that I explained terribly. This might turn out to be a pretty long post - sorry about that.

I'll start with biology.

The options are DNA viruses, Gram-negative bacteria, toxins and prions. Like i mentioned before, prions are non - cellular pathogens. This means that they are not made up of cells and thus are considered widely as not living. They are proteins.  In order to reproduce, prions need to infect a cell. If I remember correctly, they are the reason to the cause some neurological diseases. Prions are similar to viruses, they are non-cellular and are thus ruled out.Toxins are not substances which are poisonous and they are caused by bacteria and other means. So it will have to be gram-negative bacteria.


HIV attacks T-cells, yes, but not the one that you have mentioned. They attack a different type of T-cell known as a CD4 cell. While T-cells annihilate with antigens (substances that are harmful to the body), CD4 cells help plasma and memory cells of the immune system. CD4 cells are T-helper lymphocytes (which basically means a white cell).

Chemistry
A covalent bond is a bond where electrons are shared between two elements. A famous example, water, shares electrons between hydrogen and oxygen atoms. This so that the elements can "pretend" like they have a stable valence shell. I attached a picture of a water covalent bond. To know if something is a covalent bond or ionic bond, just remember that for ionic the elements have to be a metal and a non-metal, for covalent both have to be non-metal.

When the question states lose two electrons, that means like two electrons have been taken from the valence shell (kind of). So if there are 6 electrons two electrons have been lost, or taken from the valence shell, meaning that there is just 4. Since there are less electrons than if it was a neutral atom, calcium is now positively charged. It is now known as a cation.

A supernate is just a fancy name for the liquid in which the precipitate is depositied in. I have a picture of a diagram I found for your clarification.

I just realised, a reason possibly why you got the next question wrong is because of your spelling. It is Zirconium just replace the icr with irc. 

Like I said before, when any metals reacts with any acid the products have to be a salt with hydrogen gas. And if the acid is hydrochloric acid then it will
 have to be a metal chloride with hydrogen gas.

Your last question should be correct, since iron rusting is actually a chemical change. A chemical change is when the chemical properties of a substance changes while a physical change is when only the form of a substance changes.

Sorry, I'm a terrible teacher, I've told all I know about these answers. Just feel free to ask me again if you still have anything that does not seem right to you.

[Snow Leopard]

Sorry, I just realised that I explained terribly. This might turn out to be a pretty long post - sorry about that.

All good and thanks for answering my countless number of q's!

When the question states lose two electrons, that means like two electrons have been taken from the valence shell (kind of). So if there are 6 electrons two electrons have been lost, or taken from the valence shell, meaning that there is just 4. Since there are less electrons than if it was a neutral atom, calcium is now positively charged. It is now known as a cation.

I understand that it's a  cation now, but isn't the  electronic configuration of Calcium: 2,8,8,2.
Therefore, when it looses  2 electrons, wouldn't it have 8 electrons in  its outer shell. Therefore making my answer wrong.

I just realised, a reason possibly why you got the next question wrong is because of your spelling. It is Zirconium just replace the icr with irc.

Thing  is, that was a M.C question and it only had other elements as other options, so  I should've gotten it right. That's so frustrating. 

Like I said before, when any metals reacts with any acid the products have to be a salt with hydrogen gas. And if the acid is hydrochloric acid then it will have to be a metal chloride with hydrogen gas.

Sorry, I didn't  realise  you had answered this.

Your last question should be correct, since iron rusting is actually a chemical change. A chemical change is when the chemical properties of a substance changes while a physical change is when only the form of a substance changes.

That's literally making me want to pull the hair out off my head, since my teacher marked me as wrong for that one as well.

[^^^111^^^]

All good and thanks for answering my countless number of q's!
I understand that it's a  cation now, but isn't the  electronic configuration of Calcium: 2,8,8,2.
Therefore, when it looses  2 electrons, wouldn't it have 8 electrons in  its outer shell. Therefore making my answer wrong.
Thing  is, that was a M.C question and it only had other elements as other options, so  I should've gotten it right. That's so frustrating. 
Sorry, I didn't  realise  you had answered this.
That's literally making me want to pull the hair out off my head, since my teacher marked me as wrong for that one as well.

Ah yes, my bad, it should actually be 8 electrons then since calcium has two electrons in its valence shell. (Soz I was just dumb and thought that it had 6 electrons, probably thinking about water after the covalent bonding).

Idk why you have so much wrong though. If the Zirconium question was a m.c. then you must be correct. I suggest probably speaking with your teacher. Also, are they all M.C., because I had wrote my answers assuming that they are not ?