which of the following is an example of a chemical change?
cutting a log 2.
dissolving sugar
baking a cake
boiling water
Answer: Baking a Cake

Answer:

62 grams

Explanation:

Molarity=mol/liter

We have mL and Molarity

500 mL * 1 L/1000 mL=0.5

Plug 0.5 in and solve for moles

0.75=mol/0.5

0.75*0.5=0.375 mol

Convert to grams by finding the mass of KI: 39+126.9= 165.9 grams

0.375 mol KI * 165.9 grams KI/1 mol KI= 62.2125 grams

The mass of KI needed is 124.5 grams, this can be calculated by adding the values in molarity formula.

It is defined as number of moles of solute over volume of solution in liters.

It is given by:

M = n/ V

What information do we have?

Molarity= 0.750 M

Volume = 500 mL= 1 L

Molar mass of KI = 166 g/mol

To find:

Mass of KI=?

On substituting the values:

M= n/V

0.750 M= n/ 1 L

n= 0.750 M* 1l

n= 0.750 moles

Number of moles is the ratio between mass and molar mass.

n= m/M

0.750 moles = m/ 166 g/mol

m= 0.750*166

m= 124.5 grams.

Thus, the mass of KI needed is 124.5 grams.

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Answer:

6.1

Explanation:

From the question given above, the following data were obtained:

Hydrogen ion concentration [H⁺] = 8.2×10¯⁷ M

pH =?

The pH of the solution can be obtained as follow:

pH = –Log [H⁺]

pH = –Log 8.2×10¯⁷

pH = 6.1

Thus, the pH of the solution is 6.1

Answer:

10.66  grams

Explanation:

Answer:

1. Distance  = 5 cm

Displacement = 1 cm

2. Distance = 7 cm

Displacement = 1 cm

3. Distance = 5 cm

Displacement = -1 cm

4. Distance  = 6 cm

Displacement = -2 cm

5. Distance  = 4 cm

Displacement = 0 cm

Explanation:

The distance an object travels is a measure of the total ground cobpvered bybthe object without regard to the direction of motion. It is a scalar quantity as it only takes into account magnitude but not the direction of a quantity.

Displacement however, is a measure of how far away or apart an object is from its starting position.  It a vector quantity as it takes into account both the magnitude and direction in its measurement.

From the attachment provided, considering forward direction as positive and reverse as negative :

1. When a object moves from point 1 to point 4 and reverses to point 2.:

Distance  = from 1 to 4 = 3 cm; from 4 back to 2 = 2 cm;  3 + 2 = 5 cm

Displacement = from 1 to 4 = +3 cm; from 4 back to 2 = -2 cm;  3 - 2 = 1 cm

2. When an object moves from point 1 to 5 and reverses to 2:

Distance = from 1 to 5 = 4cm; from 5 back to 2 = 3 cm; 4 + 3 = 7 cm

Displacement = from 1 to 5 = +4 cm; from 5 back to 2 = -4 cm;  4 - 3 = 1 cm

3. When an object moves from point 1 to 3 and then reverses to 0.

Distance  = from 1 to 3 = 2 cm; from 3 back to 0 = 3 cm;  2 + 3 = 5 cm

Displacement = from 1 to 3 = +2 cm; from 3 back to 0 = -3 cm;  2 - 3 = -1 cm

4. When an object moves from point 3 to 5 and then reverses to 1:

Distance  = from 3 to 5 = 2 cm; from 5 back to 1 = 4 cm;  2 + 4 = 6 cm

Displacement = from 3 to 5 = +2 cm; from 5 back to 1 = -4 cm;  2 - 4 = -2 cm

5. When an object moves from point 2 to 4 and then reverses to 3.

Distance  = from 2 to 4 = 2 cm; from 4 back to 2 = 2 cm;  2 + 2 = 4 cm

Displacement = from 2 to 4 = +2 cm; from 4 back to 2 = -2 cm;  2 - 2 = 0 cm

Answer:

The answers to your questions are given below

Explanation:

F. Determination of the missing part of the equation.

_ I₂ + _Na₂S₂O₃ —> _ NaI + _ Na₂S₄O₆

The above equation can be balance as illustrated below:

I₂ + Na₂S₂O₃ —> NaI + Na₂S₄O₆

There are 2 atoms of I on the left side and 1 on the right side. It can be balance by writing 2 before NaI as shown below:

I₂ + Na₂S₂O₃ —> 2NaI + Na₂S₄O₆

There are 2 atoms of Na on the left side and a total of 4 atoms on the right side. It can be balance by writing 2 before Na₂S₂O₃ as shown below:

I₂ + 2Na₂S₂O₃ —> 2NaI + Na₂S₄O₆

Now the equation is balanced.

The coefficients are: 1, 2, 2, 1

Elements >>> Reactant >>> Product

Sodium >>>>> 4 >>>>>>>>> 4

Sulphur >>>>> 4 >>>>>>>>> 4

Oxygen >>>>> 6 >>>>>>>>> 6

Iodine >>>>>> 2 >>>>>>>>>> 2

G. Determination of the missing part of the equation.

__ Mg + __P₄ —> __Mg₃P₂

The above equation can be balance as illustrated below:

Mg + P₄ —> Mg₃P₂

There are 2 atoms of P on the right side and 4 atoms on the left side. It can be balance by writing 2 before Mg₃P₂ as shown below:

Mg + P₄ —> 2Mg₃P₂

There are 6 atoms of Mg on the right side and 1 atom on the left side. It can be balance by writing 6 before Mg as shown below:

6Mg + P₄ —> 2Mg₃P₂

Now the equation is balanced.

The coefficients are: 6, 1, 2

Elements >>>> Reactant >>> Product

Magnesium >> 6 >>>>>>>>> 6

Phosphorus >> 4 >>>>>>>>> 4

The property of water that is not critical to biological life is surface tension.

Biological life means the life in which living organism do exist and for their survival they mainly depends on water and air.

The main critical properties that water should posses to biological life are density, temperature, cohesive force and adhesive force. Viscosity is also understand by the cohesive force because more attraction between atoms more viscous they are.

Hence option (1) is correct i.e. surface tension.

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Answer:

because it may cause burn that causes acid to build up which causes you to keep having an upset stomach

Answer:

Nuclear reactions involve a change in an atom's nucleus, usually producing a different element. Chemical reactions, on the other hand, involve only a rearrangement of electrons and do not involve changes in the nuclear.

Answer: If the solubility of sodium chloride is 36 grams per 100 grams of water then 5.8 moles of NaCl dissolved in 1 L of water solution would be considered unsaturated.

Explanation:

A solution which contains the maximum amount of solute is called a saturated solution. Whereas a solution in which more amount of solute is able to dissolve is called an unsaturated solution.

Now, the number of moles present in 36 g of NaCl (molar mass = 58.4 g/mol) is as follows.

[tex]No. of moles = \frac{mass}{molar mass}\\= \frac{36 g}{58.4 g/mol}\\= 0.616 mol[/tex]

This shows that solubility of sodium chloride is 36 grams per 100 grams of water means a maximum of 0.616 mol of NaCl will dissolve in 100 mL of water.

So, a solution in which number of moles of NaCl are less than 0.616 mol per 100 mL then the solution formed will be an unsaturated solution.

[tex]Moles = \frac{5.8 mol}{1000 mL} \times 100 mL\\= 0.58 mol[/tex]

[tex]Moles = \frac{3.25 mol}{500 mL} \times 100 mL\\0.65 mol[/tex]

[tex]Moles = \frac{1.85 mol}{300 mL} \times 100 mL\\= 0.616 mol[/tex]

Thus, we can conclude that if the solubility of sodium chloride is 36 grams per 100 grams of water then 5.8 moles of NaCl dissolved in 1 L of water solution would be considered unsaturated.

Answer:

1 million years

Explanation:

The half life of a radioactive isotope refers to the time it takes for the radioactive isotope to decay to half of its original amount.

The half life of a radioactive isotope is independent of the amount of starting material. Hence, whether the amount of starting material is small or large, the half life of the substance remains the same.

Hence the half life of 2 green marbles and 500,000 green marbles is 1 million years.

Answer:

true

Explanation:

Answer:

1) Hydrogen

2) Methane

3) Carbon

4) Structural isomer

5) Ethene also known as ethylene

6) Hydrocarbons are widely used as fuel

7) Crude oil

Explanation:

Answer:

Eqv Pt pH = 8.73

Explanation:

    HOAc                   +            NaOH            =>            NaOAc              + H₂O

50ml(0.10M HOAc)  +  50ml(0.10M NaOH) => 100ml(0.05M NaOAc) + H₂O

For neutralized system, 100ml of 0.05M NaOAc remains

NaOAc => Na⁺ + OAc⁻

Na⁺ + H₂O => No Rxn

          OAc⁻  +  H₂O  => HOAc + OH⁻

C(i)   0.05M       -----        0M      0M

ΔC        -x           -----         +x        +x

C(f)    0.05-x      

       ≅ 0.05M    -----          x          x

Kb = Kw/Ka = [HOAc][OH⁻]/[OAc⁻] = 1 X 10⁻¹⁴/1.7 X 10⁻⁵ = (x)(x)/(0.05M)

=> x = [OH⁻] = SqrRt(0.05 x 10⁻¹⁴/1.7 x 10⁻⁵) = 5.42 x 10⁻⁶M

=> pOH = -log[OH⁻] = -log(5.42 x 10⁻⁶) = 5.27

pH + pOH = 14 => pH = 14 - pOH = 14 - 5.27 = 8.73 Eqv Pt pH

Answer:

1.77 * 10^-3

Explanation:

From the titration formula;

Let

CA = concentration of acid

CB = concentration of base

VA = volume of acid

VB = volume of base

NA = number of moles of acid

NB = number of moles of base

The equation of the reaction is;

M(OH)2(aq) + 2HCl(aq) -------> MCl2(aq) + 2H2O(l)

So;

CAVA/CBVB= NA/NB

CAVANB = CBVBNA

CB= CAVANB/VBNA

CB= 0.173 * 25.10 * 1/28.5 * 2

CB= 4.3423/57

CB= 0.0762 M

This implies that the solubility of M(OH)2 = 0.0762 M

M(OH)2(s) ----> M^+(aq) + 2OH^-(aq)

So

Ksp = x * (2x)^2

Ksp = 4x^3

x = 0.0762

Ksp= 4(0.0762)^3

Ksp = 1.77 * 10^-3

Answer:

The relative electronegativity of the two bonded atoms determines the polarity of a bond. If the difference in electronegativities between the two atoms is less than 0.4, the bond is nonpolar covalent. ... If the difference in electronegativities between the two atoms is more than 2.0, the bond is ionic.

Explanation:

In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions.

Answer:

25.9g

Explanation:

Molecular mass of Fe₂O₃ = (56 * 2) + (16 * 3)

                                          = 112 + 48 = 160

Let's follow the unitary method now

In 160g Fe₂O₃ , there is 112 g Fe

In 1 g  Fe₂O₃ , there is 112 / 160 g Fe

In 37  Fe₂O₃ , we need 112 * 37 / 160

= 25.9 g Fe

Answer:

a variable (often denoted by x ) whose variation does not depend on that of another.

Explanation:

You can think of independent and dependent variables in terms of cause and effect: an independent variable is the variable you think is the cause, while a dependent variable is the effect. In an experiment, you manipulate the independent variable and measure the outcome in the dependent variable.For example, someone's age might be an independent variable. Other factors (such as what they eat, how much they go to school, how much television they watch) aren't going to change a person's age.

Answer: True because if you leave it outside and it rains on the bike it will cause rust. Keep it in the garage or something. :) I have a bike btw.

Explanation:

The best way to prevent rusting is to store your bike safely away when it isn't being used and apply a rust-proofing lubricant to protect it when you are riding it – enjoying those wet and wild rides guilt-free!

so true

Answer:

Alveoli

Explanation:

I hope this helps you.

Answer:

2C8H18 + 25O2 -> 16CO2 + 18H2O

(16C, 36H, 50O)

H2O requires 2H per H2O, Meaning that you'd have 9H2O's from 1C8H18, but you still need that O2 for the CO2 and because the reactant side has 8C (within C8H18) You'd have to times the amount of required O2 from CO2 by 8. Even then you still don't have enough for both CO2 and H2O so you'll have to multiply MORE causing a bigger chain reaction resulting in 2C8H18 + 25O2 -> 16CO2 + 18H2O

Answer:D

Explanation:

The majority of explosives that forensic scientists deal with in investigations are homemade bombs. Therefore, option D is correct.

In general, forensic scientists do the following kinds of work: They examine tangible materials gathered from crime sites. They offer forensic expert testimony both before and during court proceedings. Blood, hair, and other trace evidence are gathered by investigators and sent to crime labs for analysis.

Criminalists or crime scene investigators are generalist forensic science technicians that gather evidence at the scene of a crime and conduct scientific and technical examination in labs or offices.

A forensic scientist's key responsibilities include gathering evidence at the crime scene, documenting the findings in reports, processing the evidence at the lab, and giving testimony in court.

Thus, option D is correct.

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Answer:

I think the answer will be number A

The boiling point of a substance is constant and for water it is 100 degree celsius. However by reducing the surrounding pressure the boiling point can be reduced.

Boiling point of a substances is the temperature at which the vapor pressure of the gas phase above the liquid equals to the atmospheric pressure where, the liquid converts to the vapor state.

Boiling point depends on the bond type, molar mass, temperature and pressure. As the and pressure increases, boiling point increases. Similarly with an increasing mass and more strength intermolecular force results in greater boiling point.

As the atmospheric pressure decreases, the temperature needed to equalise the vapor pressure of the gas phase over the liquid also decreases. Hence, boiling point decreases. Therefore, option C is correct.

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Answer:

The frequency is 1000 cycles/s

Explanation:

An alternating current is an electrical current in which the current changes its magnitude and the sense cyclically. The frequency of this current is defined as the cycles that the current completes in one second.

As the current completes 100 cycles in 0.1 seconds, the frequency is:

100 cycles / 0.1s = 1000 cycles /s

Answer:

Look below

Explanation:

Nitrogen: N

Phosphorus: P

Bromine: Br

Zinc: Zn

Potassium: K

Magnesium: Mg

Hope this helps(would be very grateful if you mark this answer branliest bc i need for lvl up)

Answer:

Explanation:

The temperature will only move the average velocity of all the molecules in the room. There is a limitation. The O2 molecules are heavier than the N2 molecules. The lighter the molecules, the faster they are going to move on average.

Answer:

19.3g cm^3

If it deviates from the original 19.3g cm^3