i need help with these chemistry questions .i cant do its so hard (1 Viewer)

[ashandlissy]

1) In the Periodic Table:
(A) Ionisation energy decreases from left to right.
(B) Melting points increase going up a group.
(C) Atomic radius increases across a Period.
(D) Electronegativity is higher for Cl than for Na.

2) Some metals were the first elements discovered. These included copper, lead, silver and gold. The best
reason for this is:
(A) Copper produced a green flame so it was readily found.
(B) Lead is a hard metal used for spear heads and arrows in ancient times.
(C) Silver never tarnishes (discolours) so it was always shiny on the ground.
(D) Gold is very unreactive and does not form compounds readily.

3) Alloys are useful mixtures of two or more metals. The best example is:
(A) Brass is easy to cast into shapes like door handles and knobs.
(B) Solder is used in rockets because it has a high melting point.
(G) Stainless steel is used in light bulbs as a poor conductor of electricity.
(D) Magnesium/aluminum alloy burns easily so it is used to make car wheels

4) The best method to separate pure copper metal from impure blister copper is by:
(A) Filtration
(B) Froth flotation
(C) Electrolytic refining
(B) Centrifugation

5) Two elements that are liquid and gas at room temperature are respectively:
(A) Bromine and neon
(B) Phosphorus and sulfur
(C) Lithium and mercury
(D) Iron and hydrogen

6) Chemists can place hydrogen in Group VII because it:
(A) Is a gas at room temperature.
(B) Forms diatomic molecules.
(C) Bonds covalently to non-metals.
(D) All of the above reasons.

7) Which is the correct statement about atomic structure?
(A) Electrons are negatively charged particles with a mass of 1 and found orbiting the atom.
(B) Protons have a positive charge with very little mass and found in the nucleus.
(C) Neutrons have no charge, a mass of 1 and found in the nucleus.
(D) Electrons orbit the atom in randomly filled shells.


8) Magnesium has two isotopes, Mg-24 and Mg-26. What is the % Mg-24 if the relative atomic
weight of magnesium is 24.31?
(A) 25% (B)40% (C)60% (D) 85%

9) The formation of calcium ions is best shown as follows:
(A) Ca + 2e- -> Ca2-
(B) Ca -> Ca+ + e-
(C) Ca -> 2e- + Ca2+
(D) Ca + e- -> Ca-

10) The correct formulas for the carbonate ion and hydroxide ion are respectively:
(A) CO3
2- and OH2-
(B) CO3
2- and OH-
(C) C02
3- and OH2
-
(D) C03
2+ and OH+

 

[ashandlissy]

plz help me i cannot solve all these questions

 

[adomad]

wow, must of taken you for ever to write...

are u looking for the answers or the solutions?

 

[s2 SEductive]

These questions im sure


6) Chemists can place hydrogen in Group VII because it:
(D)

9) The formation of calcium ions is best shown as follows:
(C) The electronic configuration

2,8,8,2 so we get rid of the last shellwhich is 2 too make it stable

and when we lose ions we write +

 

[ilikebeeef]

1) In the Periodic Table:
(A) Ionisation energy decreases from left to right.
(B) Melting points increase going up a group.
(C) Atomic radius increases across a Period.
(D) Electronegativity is higher for Cl than for Na.

2) Some metals were the first elements discovered. These included copper, lead, silver and gold. The best
reason for this is:
(A) Copper produced a green flame so it was readily found.
(B) Lead is a hard metal used for spear heads and arrows in ancient times.
(C) Silver never tarnishes (discolours) so it was always shiny on the ground.
(D) Gold is very unreactive and does not form compounds readily.

3) Alloys are useful mixtures of two or more metals. The best example is:
(A) Brass is easy to cast into shapes like door handles and knobs.
(B) Solder is used in rockets because it has a high melting point.
(G) Stainless steel is used in light bulbs as a poor conductor of electricity.
(D) Magnesium/aluminum alloy burns easily so it is used to make car wheels

4) The best method to separate pure copper metal from impure blister copper is by:
(A) Filtration
(B) Froth flotation
(C) Electrolytic refining
(B) Centrifugation

5) Two elements that are liquid and gas at room temperature are respectively:
(A) Bromine and neon
(B) Phosphorus and sulfur
(C) Lithium and mercury
(D) Iron and hydrogen

6) Chemists can place hydrogen in Group VII because it:
(A) Is a gas at room temperature.
(B) Forms diatomic molecules.
(C) Bonds covalently to non-metals.
(D) All of the above reasons.

7) Which is the correct statement about atomic structure?
(A) Electrons are negatively charged particles with a mass of 1 and found orbiting the atom.
(B) Protons have a positive charge with very little mass and found in the nucleus.
(C) Neutrons have no charge, a mass of 1 and found in the nucleus.
(D) Electrons orbit the atom in randomly filled shells.


8) Magnesium has two isotopes, Mg-24 and Mg-26. What is the % Mg-24 if the relative atomic
weight of magnesium is 24.31?
(A) 25% (B)40% (C)60% (D) 85%

9) The formation of calcium ions is best shown as follows:
(A) Ca + 2e- -> Ca2-
(B) Ca -> Ca+ + e-
(C) Ca -> 2e- + Ca2+
(D) Ca + e- -> Ca-

10) The correct formulas for the carbonate ion and hydroxide ion are respectively:
(A) CO3
2- and OH2-
(B) CO3
2- and OH-
(C) C02
3- and OH2
-
(D) C03
2+ and OH+

1. D
2. D
3. A
4. C
5. A
6. D
7. C
8. D
9. C
10. B

They really aren't that hard. Just do a bit of research.

EDIT: And use your calculator for Q8.

 

[adomad]

1) In the Periodic Table:
(A) Ionisation energy decreases from left to right.
(B) Melting points increase going up a group.
(C) Atomic radius increases across a Period.
(D) Electronegativity is higher for Cl than for Na.

2) Some metals were the first elements discovered. These included copper, lead, silver and gold. The best
reason for this is:
(A) Copper produced a green flame so it was readily found.
(B) Lead is a hard metal used for spear heads and arrows in ancient times.
(C) Silver never tarnishes (discolours) so it was always shiny on the ground.
(D) Gold is very unreactive and does not form compounds readily.

3) Alloys are useful mixtures of two or more metals. The best example is:
(A) Brass is easy to cast into shapes like door handles and knobs.
(B) Solder is used in rockets because it has a high melting point.
(G) Stainless steel is used in light bulbs as a poor conductor of electricity.
(D) Magnesium/aluminum alloy burns easily so it is used to make car wheels

4) The best method to separate pure copper metal from impure blister copper is by:
(A) Filtration
(B) Froth flotation
(C) Electrolytic refining
(B) Centrifugation

5) Two elements that are liquid and gas at room temperature are respectively:
(A) Bromine and neon
(B) Phosphorus and sulfur
(C) Lithium and mercury
(D) Iron and hydrogen

6) Chemists can place hydrogen in Group VII because it:
(A) Is a gas at room temperature.
(B) Forms diatomic molecules.
(C) Bonds covalently to non-metals.
(D) All of the above reasons.

7) Which is the correct statement about atomic structure?
(A) Electrons are negatively charged particles with a mass of 1 and found orbiting the atom.
(B) Protons have a positive charge with very little mass and found in the nucleus.
(C) Neutrons have no charge, a mass of 1 and found in the nucleus.
(D) Electrons orbit the atom in randomly filled shells.


8) Magnesium has two isotopes, Mg-24 and Mg-26. What is the % Mg-24 if the relative atomic
weight of magnesium is 24.31?
(A) 25% (B)40% (C)60% (D) 85% don't know...

9) The formation of calcium ions is best shown as follows:
(A) Ca + 2e- -> Ca2-
(B) Ca -> Ca+ + e-
(C) Ca -> 2e- + Ca2+
(D) Ca + e- -> Ca-

10) The correct formulas for the carbonate ion and hydroxide ion are respectively:
(A) CO3
2- and OH2-
(B) CO3
2- and OH-
(C) C02
3- and OH2
-
(D) C03
2+ and OH+

think these are right...

 

[adomad]

1. D
2. D
3. A
4. C
5. A
6. D
7. C
8. D
9. C
10. B

They really aren't that hard. Just do a bit of research.

we seem to be conflicting on Q4....

 

[ilikebeeef]

we seem to be conflicting on Q4....

It's electrolysis. Froth flotation is for separating the copper compounds from the gangue.

 

[ashandlissy]

HEY HOW DID U DO Q8

 

[ashandlissy]

is dat using calculator ?but how?

 

[ilikebeeef]

HEY HOW DID U DO Q8

is dat using calculator ?but how?

"8) Magnesium has two isotopes, Mg-24 and Mg-26. What is the % Mg-24 if the relative atomic
weight of magnesium is 24.31?
(A) 25% (B)40% (C)60% (D) 85% "

Well 24.31 is a lot closer to 24 than to 26, so a majority of it is definitely Mg-24.

I guessed that it was 85% so on my calculator I entered

24x0.85+26x0.15

and got 24.3 which is close enough to 24.31