oxidation number of Fe in Fe2(CO3)2

Explanation:

A scientific idea is an explanation for how something works, or the truth about some aspect of the world, that was figured out using the scientific process. ... Scientific ideas change over time as the evidence improves. The more experiments they do , and the more data they collect, the better the scientific ideas become.

Answer:

Here are some examples

Explanation:

NaCl

Cation = Na⁺, Anion = Cl⁻; ΔEN = |0.93 - 3.16| = 2.23

MgS

Cation = Mg²⁺, Anion = O²⁻; ΔEN = |1.31 - 3.44| = 2.53

KBr

Cation = K⁺, Anion = Br⁻; ΔEN = |0.82 - 2.96| =  2.14

CaF₂

Cation = Ca²⁺, Anion = F⁻; ΔEN = |1.00 - 3.98| = 2.98

In each case, ΔEN > 1.6, so the compound is ionic.

Answer:

[tex]\huge\boxed{King\ of \ Acid}[/tex]

Explanation:

H2SO4 (also called sulfuric acid) is also called King of Acids. It is a highly reactive acid.

Answer:

[tex]\large \boxed{\mathrm{a. \ king \ of \ acid }}[/tex]

Explanation:

[tex]\sf H_2SO_4[/tex] or sulfuric acid is known as the king of acid. It is a very reactive acid and is a strong acid in general.

Answer:

Reacting hydrogen and oxygen gases to make water

Explanation:

Exothermic means that energy is released into the environment, so let's go through the process of elimination.

Allowing meat to thaw after taking it out of the freezer - NO it is endothermic, and takes energy/heat from the environment to thaw.

Popsicle melting on a warm summer day - NO also endothermic, the opposite of exothermic.

Boiling water in a beaker to convert it to steam - NO because we need to add heat, so it doesn't release any energy.

Rolling a ball up a hill - NO, for a ball to roll up a hill, it needs energy from something else, so it's not exothermic.

Reacting hydrogen and oxygen gases to make water - YES this reaction makes new bonds, which releases energy, so this is exothermic.

Among the following choices reacting hydrogen and oxygen gases to make water is an exothermic reaction as it releases energy as new bonds are formed.

An exothermic reaction is defined as a chemical reaction which involves release of energy in the form of light,heat .In these reactions, energy is transferred from system to surroundings rather than taking energy from surroundings into system as in endothermic reactions.

In an exothermic reaction,change in enthalpy is negative.Therefore, it can be inferred that net amount of energy which is required to start the exothermic reaction is less than the net amount which is released by the reaction.

Examples of exothermic reactions are combustion reactions, detonation of nitroglycerin , neutralization reactions and nuclear fission.

Learn more about exothermic reactions,here:

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Answer:

true

Explanation:

The standard laboratory rule is to always add acids or bases to solvent and not the other way round.

The dissolution of concentrated acids/bases in solvents (water) generates heat energy. Thus, if the solvent is added to them, a layer of hot weak acid or base will be formed and this will boil and spray around, causing an explosion.

On the other hand, if acid/base is added to solvents, they flow into the solvents and get diluted immediately without any boiling taking place. Hence, it is safe to add acid/base to solvents and not the other way round.

Answer:

1.29* 10^2

Explanation:

multiply them and then round

Answer:

Chemicals are substances in any form of matter with a chemical composition and property. Chemical reaction involves the combination of two or more different atoms chemically combined together, which are not easily separated.

Explanation:

CHEMICALS

CHEMICAL REACTIONS

NEITHER

Answer:

The answer is the same as .

Explanation:

There are 3 atoms in NaOH, 1 sodium, 1 oxygen and 1 hydrogen.

There are 3 atoms in H2O, 2 hydrogen and 1 oxygen.

Answer:

CO32−

Explanation:

We have to consider the valencies of the polyatomic ions involved. Recall that it is only a polyatomic ion with a valency of -2 that can form a compound which requires two sodium ions.

When we look closely at the options, we will realize that among all the options, only CO32− has a valency of -2, hence it must be the required answer. In order to be double sure, we put down the ionic reaction equation as follows;

2Na^+(aq) + CO3^2-(aq) ---------> Na2CO3(aq)

Answer:

A).  CO32−

Explanation:

Explanation:

the intensity of a He-Ne laser (633 nm ,5 mW) transmitted by different Gase samples is observed to change in correlation with the Nd-yttrium-aluminium-garnet laser pulse (532 nm, 7.8ns ,3mJ) which excites them

Answer:

ionic

Explanation:

In NH4Cl molecule, ionic bond is formed between NH4+ and Cl– ions, 3 covalent bonds are formed between N and three H atoms and one coordinate bond is formed between N and 1 H atom.

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Answer:

[tex]\boxed{\sf c. \ ionic}[/tex]

Explanation:

NH₄Cl is formed by an ionic bond between NH₄⁺ and Cl⁻ ions.

NH₄Cl (solid) ⇒ NH4⁺ (aqueous) + Cl⁻ (aqueous)

Answer:

[tex]\boxed{\sf{view \ explanation}}[/tex]

Explanation:

Compound definition:

A compound is a chemical substance formed by two or more chemically bonded elements.

Three compounds:

Water is a compound with the formula [tex]\sf H_2O[/tex].

Two hydrogen atoms and one oxygen atom is present in one molecule of water.

Sodium chloride or table salt is a compound with the formula [tex]\sf NaCl[/tex].

One sodium atom and one chlorine atom is present in one molecule of sodium chloride.

Ammonia is a compound with the formula [tex]\sf NH_3[/tex].

In one molecule of ammonia, one nitrogen atom and three hydrogen atoms are present.

Answer:

See below

Explanation:

Three compounds are:

1) [tex]\mathrm {H_{2}SO{4}}[/tex] [Sulfuric acid]

The elements in this compound are hydrogen (H) , Sulfur (S) and Oxygen (O).

2) [tex]\mathrm {NaOH}[/tex] [Sodium hydroxide]

The elements in this compound are Sodium (Na) , Oxygen (O) and Hydrogen (H).

3) [tex]\mathrm {HCl}[/tex] [Hydrochloric acid]

The elements are Hydrogen (H) and Chlorine (Cl).

Answer:

The correct option is;

D. Manganese (Mn)

Explanation:

Manganese is very brittle, hard, iron like silvery-gray metal, that is difficult to melt. In air, Manganese slowly disintegrate in a similar manner to iron rusting in water

Manganese and iron have similar chemical and physical properties however manganese is more harder and more brittle than iron

A brittle material is one that easily breaks without deforming elastically

Therefore, manganese, due to its very iron like appearance and brittle nature will be suitable to replace the metal wall and crumble easily when the actor hits it.

Answer:

A scientific hypothesis must meet 2 requirements:

Explanation:

A scientific hypothesis must be testable, and;

A scientific hypothesis must be falsifiable.

Answer: In science, a hypothesis is a possible explanation for an observation, while a theory is an explanation that is supported by a large body of evidence.

Explanation: exact answer

Answer:

The freezing point will be -2.046°C.

Explanation:

The freezing point depression equation is [tex]\Delta T_f = k_f \cdot m \cdot i[/tex]

Where;

[tex]\Delta T_f[/tex] = The temperature depression of the freezing point

[tex]k_f[/tex]= The constant of freezing point depression which is solvent dependent = 1.86°C/m

i = The number of particles the substance decomposes into in solution = 1 for sugar (a covalent compound)

m = The molality of the solution = 1.1

Therefore, we have;

[tex]\Delta T_f = 1.86 \times 1.1 \times 1 = 2.046 ^{\circ}C[/tex]

Therefore the freezing point will be 0 - 2.046°C = -2.046°C.

Answer:

ripple marks

Explanation:

Undulation is defined as the to and fro wavelike motion in a fluid or elastic medium.

Undulation in sandy material is called ripple marks because ripple marks are the sediments of rocks that show wavy structure at its surface due to agitation by water and wind.

Hence, the correct answer is "ripple marks".

Answer:

2:A handwarmer gets warm when it is opened and exposed to air.

3:Propane ignites to heat a grill.

4:Cotton is dyed red to make a dress.

Explanation:

The definition of a chemical property is when a property of characteristic of a substance that is observed during a reaction in which a chemical has been changed

Answer:

Ingredients OR tenderising

Explanation:

Answer:

The answer is "6.68 [tex]\frac{ml} {hr}[/tex]".

Explanation:

It's going to be 18.18 kg to turn body mass to kg.  

Size 1mg / kg / hr, therefore = 1 x 18.18

                                               = 18.18 kg / hr  

now we adding 30 mg / ml of dextrose = 30 x 15

                                                                 [tex]=\frac{450mg}{15 ml +150 ml}[/tex]

of dextrose, from 15 ml to 150 ml;  

Therefore, now 450 mg in 165m:    

[tex]= \frac{ 450}{165}\\ \\=2.72 \frac{mg} {ml}[/tex]  

now divide the   18.18 by 2.72:

[tex]=\frac{18.18}{2.72}[/tex]

= 6.68 [tex]\frac{ml} {hr}[/tex]

Answer:

The body stores lipids ingested as fat and uses this energy when needed-chemical energy

A person's hat falls off and lands on the ground- gravitational energy

A wave of water pushes a surfer to shore- mechanical energy

A burner on a stove heats up a tea kettle- thermal energy

A power plant splits atoms to generate power for a city- nuclear energy

A nerve sends an impulse to another nerve- electrical energy

A plant absorbs the Sun's rays to start the process of photosynthesis- radiant energy

Explanation:

Gravitational energy is energy stored by an object as a consequence of its height.

Mechanical energy is the energy that is possessed by an object due to its motion or due to its position.

Chemical energy refers to energy stored in chemical bonds in a substance.

Thermal energy is a form of energy that exists due to temperature difference between two bodies.

Nuclear energy refers to energy stored in the nucleus of an atom.

Electrical energy is a form of energy resulting from the flow of electric charge.

Radiant energy refers to energy that moves through vacuum without passing through a material medium.

Answer:

-A molecule is the smallesr part is compound whereas a compound is the combination of two or more atoms in a fixed proportion by wiehgt.

- A glass of water is an example of compound but a small portion of water can be called molecule.

Answer:

A) The amount in grams of Li₃N produced is 1.243 g

B) N₂, is the limiting reagent

The mass of the non-limiting reagent, Li, remaining after the reaction is completed is 1.757 g

Explanation:

The given parameters are;

The mass of Li(s) = 2.5 grams

The mass of N₂ (g) = 0.5 grams

The chemical equation for the reaction can be presented as follows;

6 Li (s) + N₂ (g) → 2 Li₃N

Therefore, 6 moles of Li reacts with 1 mole of N₂  to produce 2 moles of Li₃N

The molar mass of Li = 6.941 g/mol

The molar mass of N₂ = 28.0134 g/mol

The number of moles of a reactant or product, n is given by the relation;

n = Mass of substance/(Molar mass of the substance)

For lithium, Li, n = 2.5/6.941 = 0.3602 moles

For Nitrogen gas, N₂, n = 0.5/28.0134  = 0.01785 moles

A) Given that 1 mole of  N₂ to produces 2 moles of Li₃N

0.01785  moles of  N₂ will produces 2×0.01785 = 0.0357 moles of Li₃N

The molar mass of Li₃N = 34.83 g/mol

The mass of Li₃N = 34.83 g/mol × 0.0357 moles = 1.243 g

B) 6  moles of Li reacts with 1 mole of N₂ to produce 2 moles of Li₃N

0.3602 moles will reacts with 1/6×0.3602 = 0.06003 mole of N₂

Therefore, N₂, is the limiting reagent and we have;

0.01785  moles of  N₂ will react with 6×0.01785 = 0.1071  moles of Li

The number of of moles of Li left = 0.3602 - 0.1071 =0.2531 moles

The mass of lithium left = 0.2531 moles × 6.941 g/mol = 1.757 g

The mass of lithium remaining after the reaction is completed = 1.757 g.

Answer: 89.57 %

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Answer:

blended is better than synthetic fibre. because blended fabrics have quality of synthetic and natural fibres so they are more better than fabrics. For example terrycot. Blended Fibres are considered better than individual synthetic fibres because they show the advantages of 2 or more fibres.

Answer:

a) 1.392 x 10^6 g/cm^3

b) 8.69 x 10^7 lb/ft^3

Explanation:

mass of the star m =  2.0 x 10^36 kg

radius of the star (assumed to be spherical) r = 7.0 x 10^5 km = 7.0 x 10^8 m

The density of substance ρ = mass/volume

The volume of the star = volume of a sphere = [tex]\frac{4}{3}\pi r^{3}[/tex]

==> V = [tex]\frac{4}{3}*3.142*(7.0*10^8)^{3}[/tex] = 1.437 x 10^27 m^3

density of the star ρ = (2.0 x 10^36)/(1.437 x 10^27) = 1.392 x 10^9 kg/m^3

in g/cm^3 = (1.392 x 10^9)/1000 = 1.392 x 10^6 g/cm^3

in lb/ft^3 =  (1.392 x 10^9)/16.018 = 8.69 x 10^7 lb/ft^3

Answer:

Alkalai B

Explanation:

B because its a weak alkali ie baking soda ph 8.3(sodium bicarbonate)which is used as a remeady of heartburns and stomach acids.

1 mL =[tex]10^{-3}[/tex] L

so $155$ mL =$155\times10^{-3}$ L

Now, $1$ gallon = $3.785$ L , or $1$ L= $\frac1{3.785}$ gallons

so $155\times10^{-3}$ L= $155\times10^{-3}\times \frac{1}{3.785}=40.95\times 10^{-3}$ gallons

and this is for each day, so just divide by 1 (day) to get the ratw gallons/day

i.e. $40.95\times 10^{-3}$ gal/day

Answer:

a

Explanation:

A chemical equation is said to balanced only when the number of atoms of each element is the same in both reactants and products side. Rest all options are absurd. Hence, option a is correct.

Balancing of the reaction has no relation with coefficient, molecules or charge of the elements