Which of the following is a metal? A. nitrogen

B. calcium

C. sulfur

D. carbon

 Calcium

Explanation: The chemical element Calcium (Ca), atomic number 20, is the fifth element and the third most abundant metal in the earth's crust. The metal is trimorphic, harder than sodium, but softer than aluminium.

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For #1 The Answer is (A)Calcium gives an electron to chlorine to form a stable bond.

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For #1 The Answer is (A)Calcium gives an electron to chlorine to form a stable bond.

Hope that helps :D

26- the correct answer is ( D )18

27- the correct answer is D 18 atoms
28- the correct answer is B 4 

29- the correct answer is D Zn + 2HCl→ ZnCl2 + H2 

30-∴ the correct answer is B 2

31- the correct answer is D 10 

32- the correct answer is C 2 
33- the correct answer is D HCl is the limiting reactant, 5.8 mol of H2 can be formed

34- the correct answer is B 20.6 g

35- the correct answer is C 35.88 g 

36- the correct answer is D 277 g 

37- the correct answer is C 

38- the  correct answer is C 2,1,1,2 

39- the correct answer is A) K2SO4 + 2 Ca(NO3)2→ 2KNO3 + 2CaSO4

40- The correct answer is (A ) K2S + COCl2→ 2 KCl + COS

41- the correct answer is (B) water (H2O) is always a product 

42- the correct answer is B 2.2 mol

43- the correct answer is (C) Al is the limiting reactant, 5.3 moles of H2 can be formed

44- the correct answer is (D ) 6.8 moles

45- the correct answer is A 75.4 %

some of the answers are in order below.

Explanation:

1s2 2s2 2p6 3s2 3p6 4s2 3d3

(Ar) 4s2 3d3

n=1 is the first energy level: 1s2

n=2 is the second energy level 2s2 3p6

n=3 is the third energy level 3s2 3p6 3d3

n=4 is the fourth energy level: 4s2

First ionization decreases going down the periodic table. But it increases going across the periodic table (left to right)

Electronegativity increases going across the periodic table (from left to right), and it decreases going down the periodic table.

Atomic radius increases going down the periodic table (more energy levels) and decreases going across (larger number of protons pull electrons closer to the nucleus)

A. Ionic bond_B_ Sharing of electrons

B. Covalent bond_C Freely moving electrons

C. Metallic bond_A_ Transfer of electrons

A dipole –dipole forces are occurring between positive end of one polar molecule and a negative end of another polar molecule.

Hydrogen bonding is when hydrogen atom bonded to oxygen, nitrogen or fluoride is attracted to another oxygen, nitrogen or fluoride atom.

Van der Waals forces are intermolecular forces that form because there is fluctuation within an electric cloud, with more electrons on one side of an atom then the other causing slight polarity in nonpolar molecules.

The cell membranes are non-polar lipids, and polar molecules cannot pass through it easily. Some small polar molecules (medicine) can diffuse through the lipid layer easily but larger cannot. (research more)

The strongest bond is H –H bond. The weakest is I-I bond.

These are the measures of average bond energies of the most common bonds present.

S can bond with I and N in many different bond energies.

Triple bond has the highest bonding energy and it is the strongest bond, then double and the weakest is single bond.

etc etc..

some of the answers are in order below.

Explanation:

1s2 2s2 2p6 3s2 3p6 4s2 3d3

(Ar) 4s2 3d3

n=1 is the first energy level: 1s2

n=2 is the second energy level 2s2 3p6

n=3 is the third energy level 3s2 3p6 3d3

n=4 is the fourth energy level: 4s2

First ionization decreases going down the periodic table. But it increases going across the periodic table (left to right)

Electronegativity increases going across the periodic table (from left to right), and it decreases going down the periodic table.

Atomic radius increases going down the periodic table (more energy levels) and decreases going across (larger number of protons pull electrons closer to the nucleus)

A. Ionic bond_B_ Sharing of electrons

B. Covalent bond_C Freely moving electrons

C. Metallic bond_A_ Transfer of electrons

A dipole –dipole forces are occurring between positive end of one polar molecule and a negative end of another polar molecule.

Hydrogen bonding is when hydrogen atom bonded to oxygen, nitrogen or fluoride is attracted to another oxygen, nitrogen or fluoride atom.

Van der Waals forces are intermolecular forces that form because there is fluctuation within an electric cloud, with more electrons on one side of an atom then the other causing slight polarity in nonpolar molecules.

The cell membranes are non-polar lipids, and polar molecules cannot pass through it easily. Some small polar molecules (medicine) can diffuse through the lipid layer easily but larger cannot. (research more)

The strongest bond is H –H bond. The weakest is I-I bond.

These are the measures of average bond energies of the most common bonds present.

S can bond with I and N in many different bond energies.

Triple bond has the highest bonding energy and it is the strongest bond, then double and the weakest is single bond.

etc etc..

See explanation

Explanation:

Sea water = a mixture of different substances in water. If the water evaporates, some of those substances remain as salts. It's not a compound because it's a mixture of compounds and substances. An example of a compound is water ( because it has hydrogen atoms and an oxygen atom)

Calcium = Calcium is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because we can find it on the left side of the periodic table, in group 2.  It's an alkaline earth metal, what makes that calcium is a reactive metal.

Argon = Argon is found on the periodic table, so it can't be a mixture or compound. It is a non-metallic element. We can find it in group 18 on the periodic table. Argon is a noble gas, so non-metallic.

Water = a compound because its only made of 2 atoms : oxygen and hydrogen.  Reasons why water is a compound and not a mixture are:

 - The ormation of a compound is a chemical change which is followed by absorption of energy or evolution of energy, in case of water, electricity is required.

- Mixtures can be separated by physical separation techniques ,Water can not be separated into it its elements by physical separation techniques. But by the absorption of chemical energy.

Air = Mixture because it can be separated into different atoms, molecules,..  like oxygen, nitrogen etc. by the physical separation techniques (fractional distillation).

Carbon Monoxide = Carbon Monoxide is not found on the periodic table so it cannot be an element. It's made of 2 elements, this means caron monoxide is a compound. It's not a mixture since the elements cannot be separated by physical separating techniques.

Iron = Iron is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:

-High melting point

-  Some metals form a dull oxide layer, this explains the shiny luster surface

- Electrical conductivity and thermal conductivity

Sodium chloride = NaCl cannot be found on the periodic table, so it isn't an element. It's a compound because it only has 2 atoms (elements). Those elements cannot be seperated by physical separating techniques, but would require electricity. So it's a compound.

Diamond = is a solid form of the element Carbon.  It's an allotrope of carbon. They have the same physical state but in distinct form. Technically diamond is a non-metallic element. Since it's seen as carbon.

Brass = Brass is a mixture of the elements of copper and zinc. Those elements can be separated by physical techniques.

Copper = Copper is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:

-High melting point

-  Some metals form a dull oxide layer, this explains the shiny luster surface

- Electrical conductivity and thermal conductivity

Dilute sulphuric acid = This is a mixture. Sulphuric acid is a compound but to dilute it's added in water, what is another compound. So it's a mixture of different compounds.

Sulphur = Can be found in the periodic table so it cannot be a mixture or compound. It's part of the metalloids, therefore, it can be concluded that sulfur is a non-metal. It belongs to the oxygen family.

Oil = Oil is a mixture of hydrocarbon compounds which varies in lengths.

Nitrogen = Nitrogen is found on the periodic table, so it can't be a mixture or compound. It can be found as a gas so it is a non-metallic element.

Ammonia = a compound of nitrogen and hydrogen with the formula NH3. Those elements cannot be separated with physical separating techniques.

26- the correct answer is ( D )18

27- the correct answer is D 18 atoms
28- the correct answer is B 4 

29- the correct answer is D Zn + 2HCl→ ZnCl2 + H2 

30-∴ the correct answer is B 2

31- the correct answer is D 10 

32- the correct answer is C 2 
33- the correct answer is D HCl is the limiting reactant, 5.8 mol of H2 can be formed

34- the correct answer is B 20.6 g

35- the correct answer is C 35.88 g 

36- the correct answer is D 277 g 

37- the correct answer is C 

38- the  correct answer is C 2,1,1,2 

39- the correct answer is A) K2SO4 + 2 Ca(NO3)2→ 2KNO3 + 2CaSO4

40- The correct answer is (A ) K2S + COCl2→ 2 KCl + COS

41- the correct answer is (B) water (H2O) is always a product 

42- the correct answer is B 2.2 mol

43- the correct answer is (C) Al is the limiting reactant, 5.3 moles of H2 can be formed

44- the correct answer is (D ) 6.8 moles

45- the correct answer is A 75.4 %

See explanation

Explanation:

Sea water = a mixture of different substances in water. If the water evaporates, some of those substances remain as salts. It's not a compound because it's a mixture of compounds and substances. An example of a compound is water ( because it has hydrogen atoms and an oxygen atom)

Calcium = Calcium is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because we can find it on the left side of the periodic table, in group 2.  It's an alkaline earth metal, what makes that calcium is a reactive metal.

Argon = Argon is found on the periodic table, so it can't be a mixture or compound. It is a non-metallic element. We can find it in group 18 on the periodic table. Argon is a noble gas, so non-metallic.

Water = a compound because its only made of 2 atoms : oxygen and hydrogen.  Reasons why water is a compound and not a mixture are:

 - The ormation of a compound is a chemical change which is followed by absorption of energy or evolution of energy, in case of water, electricity is required.

- Mixtures can be separated by physical separation techniques ,Water can not be separated into it its elements by physical separation techniques. But by the absorption of chemical energy.

Air = Mixture because it can be separated into different atoms, molecules,..  like oxygen, nitrogen etc. by the physical separation techniques (fractional distillation).

Carbon Monoxide = Carbon Monoxide is not found on the periodic table so it cannot be an element. It's made of 2 elements, this means caron monoxide is a compound. It's not a mixture since the elements cannot be separated by physical separating techniques.

Iron = Iron is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:

-High melting point

-  Some metals form a dull oxide layer, this explains the shiny luster surface

- Electrical conductivity and thermal conductivity

Sodium chloride = NaCl cannot be found on the periodic table, so it isn't an element. It's a compound because it only has 2 atoms (elements). Those elements cannot be seperated by physical separating techniques, but would require electricity. So it's a compound.

Diamond = is a solid form of the element Carbon.  It's an allotrope of carbon. They have the same physical state but in distinct form. Technically diamond is a non-metallic element. Since it's seen as carbon.

Brass = Brass is a mixture of the elements of copper and zinc. Those elements can be separated by physical techniques.

Copper = Copper is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:

-High melting point

-  Some metals form a dull oxide layer, this explains the shiny luster surface

- Electrical conductivity and thermal conductivity

Dilute sulphuric acid = This is a mixture. Sulphuric acid is a compound but to dilute it's added in water, what is another compound. So it's a mixture of different compounds.

Sulphur = Can be found in the periodic table so it cannot be a mixture or compound. It's part of the metalloids, therefore, it can be concluded that sulfur is a non-metal. It belongs to the oxygen family.

Oil = Oil is a mixture of hydrocarbon compounds which varies in lengths.

Nitrogen = Nitrogen is found on the periodic table, so it can't be a mixture or compound. It can be found as a gas so it is a non-metallic element.

Ammonia = a compound of nitrogen and hydrogen with the formula NH3. Those elements cannot be separated with physical separating techniques.