Select the correct answer.In which research method does a researcher change the value of one variable to determine how the change affects another variable?
O A experiment
OB. observational research
Oc.
survey
OD
case study

Answer:

The electrons are lost from the valence shell (outermost electron shell) of the atom.

Explanation:

This is able to be inferred not only because valence electrons being lost first is a trend but also because the atom in question has actually 3 valence electrons (13-2-8 = 3).

Answer:

Question 1

Answer ;

in photosynthesis process, the plant have the ability to absorb the light using their pigment called as chlorophyll.  this light energy with the help of many enzymes will help the conversion of CO2 and water in to glucose  which is then transported to different parts of the plants for its usage in different cellular processes and growth. The excess of glucose which is not utilized and metabolized immediately is converted to complex sugar molecules and stored in the plant in the form of Starch to fulfill the future needs.

Question 2

Answer ;

starch are stored for many purpose. the pathway used to create and store glucose in the form of starch is a reversible process. if potato plant have not made enough glucose for the day to feed itself, the starch which was stored will be catabolized using different cellular enzymes in to glucose.the starch which is stored is broken down and needed in those conditions and days when there is no sunlight or cloudy weather for days.

Answer:

a) Warmer

b) Exothermic

c) -10.71 kJ

Explanation:

The reaction:

KOH(s) → KOH(aq) + 43 kJ/mol

It is an exothermic reaction since the reaction liberates 43 kJ per mol of KOH dissolved.

Hence, the dissolution of potassium hydroxide pellets to water provokes that the beaker gets warmer for being an exothermic reaction.

The enthalpy change for the dissolution of 14 g of KOH is:

Where:

m: is the mass of KOH = 14 g

M: is the molar mass = 56.1056 g/mol

The enthalpy change is:

The minus sign of 43 is because the reaction is exothermic.

I hope it helps you!

Answer:

its not more kinetic energy i put that and got it wrong

Answer:

0.113 M

Explanation:

Since B and D are on opposite sides of the reaction, the concentration of D increases when the concentration of B decreases. The amount by which D increases is determined by the coefficients of B and D in the balanced chemical equation:

[D]=(0.045 M)=0.113 M.

Answer:

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 = CarbonMonoxide 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.