CHEMISTRY HIGH SCHOOL

Which process is a chemical change?(1) melting of ice
(2) boiling of water
(3) subliming of ice
(4) decomposing of water

Answers

Answer 1
Answer:

Answer:

Option 4 = decomposing of water

Explanation:

Chemical change:

The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.

These changes are irreversible.

These changes occur due to chemical reactions.

These may not be observed with naked eye.

Example:

Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood

Boiling of egg: that change the chemical composition of protein in the egg

The reaction of Hydrogen and oxygen:

H 2 (g)  + O 2  (g) -------------------------------------> 2H 2O  (l)

Physical Change                                                                                              

The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.

These changes were reversible.

They have same chemical property.

These changes can be observed with naked eye.

Example

Water converting to Ice.

Water converting to gas.

In this water molecule remain the same only they rearrange themselves that change its state of mater not composition.

1 = Melting of ice

The melting of ice is physical change because water molecules are just change the state from solid to liquid and composition remain same.

2 = Boiling of water

It is also a physical change because water molecules are just change the state from liquid to gas and the molecular structure of water molecules remain same.

3 = Subliming of ice

It is physical change because ice is converted into water vapors without going through liquid phase.

4 = Decomposing of water

It is a chemical change because water molecules are split into the hydrogen and oxygen. The molecular structure is changed. New product is formed which is different from the reactant.

Related Questions

Who developed a way of showing valence electrons?
object a at 40 degrees C and object b at 80 degrees C are placed in contact with each other which statement descibes the heat flow between the objects
Potato strips placed in a container of concentrated salt water will ultimately __.
Which statement describes a property of covalent compounds? They have a high boiling point because of strong intermolecular forces. They have a low boiling point because of weak intermolecular forces. They have a low melting point because of strong intermolecular forces. They have a high melting point because of weak intermolecular forces.
Hypobromite is used to purify contaminated water. what is the formula for hypobromite

How did Diocletian try to improve Rome’s economy

Answers

He divided the empire into provinces. 

The empirical formula of styrene is CH; find the % composition for H and CH. How many atoms are present in a 2.00 gram sample of styrene? PLEASE HELP! THANK YOU

Answers

% Composition = ?
no atom in 2 g of styrene =? 
molar mass of strene =104.15
% composition of c= 12/13.008 =.922*100=92.2
% composition of h =1.008/13.008=0.0774*100= 7.74

no gram atom=mass in kg /molar mass=2/104.15 =0.01920 mol
no of gram atom * avogadro's number  = 0.0192*6.02 *10( exponent 23) =1.15584 

Which tiny, round “factory” puts together protein and is often found in the endoplasmic reticulum?A.
chromosome


B.
chloroplast


C.
Golgi body


D.
ribosome

Answers

In the cytoplasm, ribsomal RNA (rRNA), a type of RNA, andprotein combine to form a nucleoprotein called a ribosome. The ribosomeserves as the site and carries the enzymes necessary for proteinsynthesis. They are often takes the shape of small round particlesattached in the endoplasmic reticulum. The ribosome attaches itself to m-RNAand provides the stabilizing structure to hold all substances in position asthe protein is synthesized. Several ribosomes may be attached to a single RNAat any time.   
i believe that the answer is B , chloroplast. you can work out the problem any other wat too.

i hope this helps

As the density of a substance increases, the volume of a given mass of that substance__.a. Increases
b. is not affected
c. decreases
d. fluctuates

Answers

Answer : The correct option is, (C) decreases

Explanation :

As we know that the density is measured as the mass of substance divided by the volume of substance. The S.I unit of density is, kilogram per cubic meter or Kg/m^3

Formula for density :

\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}

That means the density is directly proportional to the mass of the substance and inversely proportional to the volume of the substance.

As the volume of substance decreases, the density of a substance will be increases and volume of substance increases, the density of a substance will be decreases.

Hence, the correct option is, (C) decreases
As the density of a substance increases the volume of a givenmass of the substance decreases

Which substance can be decomposed by chemical means?(1) ammonia (3) phosphorus
(2) oxygen (4) silicon

Answers

\boxed{\left( 1 \right){\text{ ammonia}}} is the substance that can be decomposed by chemical means.

Further Explanation:

The pure form of matter is defined as substance but the mixture is termed as the combination of atoms and molecules.

Classification of substances:

(a). Element

It is a type of pure substance and is the simplest form that cannot be broken down by any chemical means. Copper, iron, and aluminium are some of the examples of elements.

(b) Compound

It is composed of two or more different elements that are held together by chemical bonds. These can be decomposed into their respective constituents. Compounds have no similarity in properties with those of their constituent particles. NaCl, {\text{C}}{{\text{O}}_{\text{2}}} and {\text{N}}{{\text{H}}_3} are examples of compounds.

(1) Ammonia contains one nitrogen and three hydrogen atoms so it is a compound. Since compounds can be decomposed chemically, ammonia is also decomposed by chemical means.

(2) Oxygen (O) is an element so it is the simplest form in which it can exist. Therefore it cannot be decomposed by chemical means.

(3) Phosphorus (P) is an element so it is the simplest form in which it can exist. Therefore it cannot be decomposed by chemical means.

(4) Silicon (Si) is an element so it is the simplest form in which it can exist. Therefore it cannot be decomposed by chemical means.

Learn more:

  1. Give an example of a two-phase mixture: brainly.com/question/838401
  2. Which sample is a pure substance? brainly.com/question/2227438

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Elements, compounds, and mixtures

Keywords: substance, ammonia, oxygen, phosphorus, silicon, element, compound, chemical means, decomposed, broken down, simplest form.

Final answer:

Ammonia is a compound composed of nitrogen and hydrogen, and as such, can be chemically decomposed into these elements. Oxygen, phosphorus and silicon, being elements, cannot be decomposed by chemical means.

Explanation:

In the context of chemistry, a substance can be decomposed by chemical means if it is a compound. Compounds are composed of two or more different elements and can be broken down into those elements through chemical reactions. In the given options, (1) ammonia is a compound, composed of nitrogen and hydrogen elements. Therefore, ammonia can be chemically decomposed into its constituent elements. In contrast, oxygen, phosphorus, and silicon are all elements, which means they cannot be decomposed further by chemical means.

Learn more about Decomposition of Substances here:

brainly.com/question/31730584

#SPJ6

ure carbon tetrachloride, CCl4, freezes at-23.00 ⁰C and has a kf of 29.8⁰C/m. The latest lot has a freezing point of-23.43⁰C. What is the molality of impurities in thesolvent? If the impurity is largely hexachloroethane, C2Cl6, how many grams of this impurity arethere per kg of CCl4?Once the mass of the impurity is determined, calculate the mass % purity:

Answers

Answer:

a) grams of this impurity per kg of CCl4 = 3.416 g/kg of solvent.

b) mass purity % = 99.66%

Explanation:

Given, the freezing point of pure CCl₄ = - 23°C

Presence of impurities lowers the freezing point to - 23.43°C

The freezing point depression constant, Kբ = 29.8°C/m

The lowered freezing point is related to all the parameters through the relation

ΔT = i Kբ × m

where ΔT is the lowered freezing point, that is, the difference between freezing point of pure substance (T⁰) and freezing point of substance with impurities (T).

i = Van't Hoff factor which measures how much the impurities influence/affect colligative properties (such as freezing point depression) and for most non-electrolytes like this one, it is = 1

Kբ = The freezing point depression constant = 29.8°C/m

m = Molality = ?

T⁰ - T = i Kբ m

- 23 - (-23.43) = 1 × 29.8 × m

m = 0.43/29.8 = 0.0144 mol/kg

Them we're told to calculate impurity of the CCl₄

we convert the Molality to (gram of solute)/(kg of solvent) first

Solute = C₂Cl₆

Molar mass = 236.74 g/mol

So, (molality × molar mass) = (gram of solute)/(kg of solvent)

(gram of solute)/(kg of solvent) = 0.0144 × 236.74 = 3.416 (gram of solute)/(kg of solvent)

Mass purity % = (1000 g of pure substance)/(1000 g of pure substance + mass of impurity in 1000 g of pure substance)

1000 g of solvent contains 3.416 grams of impurities

Mass purity % =100% × 1000/(1003.416)

Mass purity % = 99.66 %
Other Questions
Based on its location on the periodic table, which metal is likely to be less reactive than both strontium and sodium?A. magnesium (Mg) B. barium (Ba) C. cesium (Cs) D.rubidium (Rb)
#1: The concentration of a solution can be described in several ways. In which of these ways do you calculate the moles of a solute divided by the kilograms of solvent? A. molality B. molarity C. mole fraction D. mass percent
Tin reacts with nitric acid according to the following equation. What substance is the reducing agent? Sn(s) + 4HNO3(aq) → SnO2(s) + 4NO2(g) + 2H2O(g)
Find the density of evaporated milk if 411 grams occupy 384 cm^3