In comparing groups, the first or the second, which group was more precise or was the precision the same

Answer:

Four seasons occur on Earth

Explanation:

When the Earth has completely one revolution around the Sun, then it has completed 1 year, and four seasons have occurred in the meantime.

Four seasons occur on Earth when the Earth completes a revolution around the Sun.

The following points can be considered:

Therefore the correct answer is Four seasons occur on Earth.

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Answer:

this answer is b no u can it very easy

Explanation:

because solid and liquid can compress easily

plz support me

Answer:

A. move very little, so it cannot easily change its shape.

Answer:

oooooooooougifufofhhdykddykyd

Answer:

b.troposphere

Explanation:

pls mark me brainliest

Answer:

15000000

Explanation:

30000 x 500=15000000. I believe... lemme know if I was wrong, hope this helps <3.

Answer:

2C2H2 + 5O2 → 4CO2 + 2H2O

Explanation:

Answer:

it's yellowish in color plz Mark me as brainliest

Answer:

It's a yellowish color like copper

Answer:

The empirical formula is the formula with a minimum whole number ratio of the constituent atoms present in a molecule. While the molecular formula has the actual number of atoms of various elements present in the molecule of the substance.

Empirical formula is C₃H₄O₃

Molecular formula is C₆H₈O₆

[tex]C_{x}[/tex][tex]H_{y} O_{z}[/tex] + O₂ ⟶ xCO₂ + [tex]\frac{y}{z} H_{2} O[/tex]

From online sources, molar mass of CO₂ = 44 g/mol

number of moles of CO₂ = 12.81/44 = 0.291m mol

Mass of carbon in it is; C = 12 × 0.291 = 3.492 mg

molar mass of water = 18 g/mol

number of moles of water in it = 3.5/18 = 0.194m mol

Hydrogen has 2 nos in water and so;

number of moles of hydrogen = 2 × 0.194 = 0.388m mol

Mass of hydrogen = 1 × 0.388 = 0.388 mg

Oxygen mass = 8.544 - (3.492 + 0.388) = 4.664 mg

Similarly, moles of oxygen that has molar mass of 16 is;

no of moles of oxygen = 4.664/16 = 0.2915m mol

Ratio of C:H:O is; 0.291:0.388;0.2915

Simplifying this gives us the empirical formula ratio as;

3:4:3

Thus;

Empirical formula is C₃H₄O₃

We are told that the molar mass of the compound is 176.1 g/mol.

Thus;

Molecular formula is; (176.1/88)C₃H₄O₃ = C₆H₈O₆

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Answer:  132 liters. or 130 liters with 2 sig figs.

Explanation:  Use the ideal gas law:  PV = nRT

We want V, so rewrite and plug in data:

Temperture must be in Kelvin (add 273.15 to

V = (nRT)/P

V = (4.9 moles)*(0.0821 L*atm/molK)*(328.2K)/(1atm)

V = 132 liters (3 sig figs).  130 liters with 2 sig figs

The number of moles of reactants and products can be used to obtain the mass of products formed. The results obtained are as follows;

The question says that HCl was in excess. It means that after the reaction, we will have unreacted HCl(aq) and  ZnCl2(aq) in the remaining solution.

Hence;

Mass of ZnCl2(aq) formed = 36.309g - 35.123g  = 1.186g

Number of moles ZnCl2(aq) formed = [tex]\frac{mass of ZnCl2(aq) formed}{molar mass of ZnCl2}[/tex]

[tex]\frac{1.186g}{136.286 g/mol}[/tex] = 0.0087 moles

From the reaction equation;

[tex]Zn (s) + 2HCl(aq) - > H2(g) + ZnCl2 (aq)[/tex]

To obtain the amount of Zn reacted

1 mole of Zn yields 1 mole of ZnCl2

x moles of Zn yields 0.0087 moles of ZnCl2

x = 0.0087 moles of Zn

a) 1 mole of Zn yields 1 mole of H2

0.0087 moles of Zn yields 0.0087 moles of H2

Mass of H2 = 0.0087 moles of H2 * 2 g/mol = 0.0174 grams

b)

Mass of Zn reacted =  0.0087 moles of Zn * 65.38 grams/mole = 0.5688 grams

c)

Percentage of Zn in the alloy = 0.5688 grams/1.203g * 100 = 47.3 %

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Answer:

7500000cm/hr

Explanation:

6km=600000cm

24min=24/60hr=0.4hr

so, according to the question

6k/24km=600000cm÷0.4hr

=1500000cm/hr

therefore in 5 hours we can run:

5×1500000cm/Hr

=7500000cm/hr

A person can run "7,500,000 cm" in 5 hours.

According to the question,

A person can run 6 km in 24 minutes, i.e.,

= [tex]\frac{6}{24} \ km/min[/tex]

and,

5 hours = 300 minutes

then,

→  A person can run in 5 hours:

= [tex]\frac{6}{24}\times 300[/tex]

= [tex]\frac{1800}{24}[/tex]

= [tex]75 \ km[/tex]

By converting km into cm, we get

= [tex]7500000 \ cm[/tex]

So the above is the right answer.

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Answer:

It would take sound 104.998 seconds to travel across lake tahoe.

Explanation:

First let's convert the miles to meters, so, 21.6 miles = 34754.4 meters

Now, we will divide this number in meters by 331. So, 34754.4 / 331 = 104.998

And what will the unit be? Seconds will be the unit for time here so 104.998 seconds.

Answer:

B bcx is a way of separating different crystals from each other and the other is a way of separating different crystals from each other and the other

Explanation:

Volume = FL - SL

= 39 - 33

= 6

Answer:

white

Explanation:

The product of a chemical reaction is what is remaining at the end of the reaction. The combination between reactant to form products can happen in a variety of ways including combination of ions in a solution to form new compounds

The correct compounds representing the variables and the net ionic equations are as follows:

a) A = NaCl

B = H₂O

Balanced net ionic equation: OH⁻(aq) + H⁺(aq) → H₂O (l)

ΔHrxn = Negative

b) C = NH₃

D = NaCl(aq)

E = H₂O(l)

Balanced net ionic equation: OH⁻(aq) + NH₄⁺(aq) → NH₃(aq) + H₂O(l)

ΔHrxn = Negative

c) F = NH₄Cl(aq)

Balanced net ionic equation: H⁺(aq) + NH₃(aq) → NH₄⁺(aq)

ΔHrxn = Negative

The reason the above values are correct are as follows:

a) Part (i)

The given chemical equation is

NaOH(aq) + HCl(aq) → A(aq) + B(l)

The chemical equation is the reaction between sodium hydroxide NaOH (aq) and hydrochloric acid HCl (aq), the product of the reaction is sodium chloride and water as follows;

NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l) + Heat

Therefore, we have;

A = NaCl, and B = H₂O

Part (ii)

The ionic equation is given as follows;

Na⁺(aq) + OH⁻(aq) + H⁺(aq) + Cl⁻(aq) → Na⁺(aq) + Cl⁻(aq) + H₂O (l)

Given that Na⁺(aq) and Cl⁻(aq) are spectator ions in the reaction, we have the balanced net ionic equation given as follows;

Balanced net ionic equation: OH⁻(aq) + H⁺(aq) → H₂O (l)

Part (iii)

ΔHrxn = Negative

b) Part (i)

The given chemical equation is NaOH(aq) + NH₄Cl(aq) → C(aq) + D(aq) + E(l)

The given reaction is between sodium hydroxide, NaOH(aq) and ammonium chloride, NH₄Cl(aq) and the products of the reaction are dissolved ammonia NH₃(aq), sodium chloride NaCl(aq), and water H₂O(l)

Therefore, we have;

NaOH(aq) + NH₄Cl(aq) → NH₃(aq) + NaCl (aq) + H₂O(l) + Heat

Therefore;

C = NH₃, D = NaCl(aq), E = H₂O(l)

Part (ii)

The ionic equation for the reaction is given as follows;

Na⁺(aq) + OH⁻(aq) + NH₄⁺(aq) + Cl⁻(aq) → NH₃(aq) + Na⁺(aq) + Cl⁻(aq) + H₂O(l)

The Na⁺(aq) and Cl⁻(aq) occur in both the reactants and products, therefore, they cancel out as spectator ions and we have;

Balanced net ionic equation: OH⁻(aq) + NH₄⁺(aq) → NH₃(aq) + H₂O(l)

Part (iii)

ΔHrxn = Negative

c) Part (i)

HCl(aq) + NH₃(aq) → F(l)

The given reaction is between hydrochloric acid and aqueous ammonia which has the product as ammonium chloride, NH₄Cl

Therefore, the reaction is given as follows;

HCl(aq) + NH₃(aq) → NH₄Cl(aq) + Heat

∴ F = NH₄Cl(aq)

Part (ii)

The ionic equation is given as follows;

H⁺(aq) + Cl⁻(aq) + NH₃(aq) → NH₄⁺(aq) + Cl⁻(aq)

Therefore, the chlorine ion Cl⁻(aq) occurs in both the reactant and product and can therefore, can be canceled out, and we have;

Balanced net ionic equation: H⁺(aq) + NH₃(aq) → NH₄⁺(aq)

Part (iii)

ΔHrxn = Negative

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Answer:

1.. Lanthanides and actinides are kept separately in the modern periodic table Why?

Lanthanides and actinides are kept separately in the modern periodic table because of following reason:

Explanation:

2. Differentiate between long period and short period in any two points.

Long period:

short period:

Answer:

Density=mass/volume

= 570/2280

=0.25g/ml

Answer:

1, just I) color.

Explanation:

Physical properties are the properties that can be observed without changing the composition of a substance, such as color, temperature, density, and boiling point.

A physical change is a change in the substance that only modifies its aggregation state, such as solidification, and boiling.

Chemical properties are the properties that need a reaction to being observed, such as combustibility, which needs a combustion reaction to being quantified.

When a chemical reaction occurs, and the composition of the substance change, it's a chemical change.

So, heating copper with carbon is a chemical reaction, and purification by electrolysis is too. Color is the only physical property.

Answer:

Explanation:

Data are the facts, figures, and other evidence gathered through observations.

Answer:

you tilt the cylinder at a slight angle so that the metal slides down the sides, rather than drops all it`s weight to the bottom

Answer:

~58.3 mL

Explanation:

m1*v1=m2*v2 --> (12.0 M HCL) * v1 = 350mL * 2.0M HCL

--> 350*2.0 = 700

--> 700/12.0 M HCL = 58.3 mL repeating

Answer:

2

Explanation:

2×2

2O

soooo

2H2O means 4H2O

Answer:

The empirical formula is the simplest form;

Given:

Oxygen O at 94.1% and

H at 5.9%

Assume 100grams.

94% = 0.941 x 100gm. = 94.1 gm x 1mole/16gm. = 5.88 moles of O

5.9% = 0.059 x 100gm. = 5.9gm. X 1moleH/1.002gm. = 5.88 moles of H

There is one mole of O for each mole of H so the empirical formula is [tex]O_1H_1[/tex]

and written as OH.

Explanation:

[tex]given \: that \: oxygen \: by \: 94.1\% (.941)\\ hydrogen \: by5.9\%(.059) \\ in \: 100gram \: \\ oxygen = 100 g\times .941 = 94.1 \times \frac{1(mol)}{16g} \\ = 5.88moles \: of \: oxygen \\ in \: hydrogen \: = .059\times 100 = 5.9 \times \frac{1mol}{1.002gram} \\ = 5.88mole \: of \: hydrogen \\ \: so \: here \: \: both \: oxygen \: andhydrogen = 5.88 \\their \: ratio = 1 \: 1 \\ so \: emparical \: formula = oh \\ thank \: you[/tex]

Answer:

1.23x10^24 atoms/6.022x10^23 atom/mol = 2.04 mol H20

Explanation:

Answer:

density is the sum of the mass and volume of an object

Answer:

13.8g

Explanation:

Remember that density is equal to mass over volume

d=m/v

rearrange the problem and you get dv=m

(0.92g/mL)(15mL)=13.8g