2×21=how many are there​

Answers

Answer 1
Multiply 2 * 21

2 * 21
= 42

Related Questions

the Central value of the set of observation is called.​

Answers

Answer:

The central value of the sets of observation can be mean, median or mode depending upon the kind of data provided as all are measure of central tendency.

Explanation:

If hydrochloric acid has a [H+] of 1.2 x 10-2 M, what is the pH?
1.9
0 1
1.2
O
8

Answers

Answer:

1.9

Explanation:

The pH of a solution can be found by using the formula

[tex]pH = - log [ {H}^{+} ][/tex]

From the question we have

[tex]pH = - log(1.2 \times {10}^{ - 2} ) \\ = 1.920818...[/tex]

We have the final answer as

1.9

Hope this helps you

Answer:

1.9

Explanation:

9.
How would your mass and weight differ on the moon? (The gravitational force on the
moon is 1/6 the force on Earth).-

Answers

Answer: Your mass would be the same, but you would weigh less because the gravity on the moon is less than it is on Earth.

Explanation:

Which of the following is true about nuclear fusion
a) it occurs in the sun
b) a heavy atom is split
c) it can be controlled easily
d) an electron is lost by the atom

Answers

Answer:

 i would assume that it would be (a)

Explanation:

The Sun generates its energy by nuclear fusion

NUCLEAR FISSION is when the heavy atom is split

fusion energy is scientifically feasible. Plasma conditions that are very close to those required in a fusion reactor are now routinely reached in experiments

mass gets lost is nuclear fusion

so (a) is the most accurate

Answer:

it occurs in the sun

Explanation:

just took the test so its A. GL!

is methane used as fule
gas true or false

Answers

Answer:

its true methane is used as a fuel gas

Explanation:

Is NaHCO3 a compound? Explain pls!

Answers

Answer:

Yes it is

Explanation: because it is composed of identical molecules consisting of atoms of two or more chemical elements.

hope it helps <3

Which formula represents a polar molecule? 1. O2 2. CO2 3. NH3 4. CH4

Answers

Answer:

NH3.

Explanation:

You can draw Lewis diagrams to answer this question and what distinguishes a polar from a nonpolar molecule: A nonpolar molecule must be symmetric and have no lone pairs on its central atom. The only one that fits the criteria necessary to be a polar molecule is NH3.

The chemical formula which represents a polar molecule is NH₃ as there is charge separation in the molecule.

What is chemical formula ?

Chemical  formula is a way of representing the number of atoms present in a compound or molecule.It is written with the help of symbols  of elements. It also makes use of brackets and subscripts.

Subscripts are used to denote number of atoms of each element and brackets indicate presence of group of atoms. Chemical formula does not contain words. Chemical formula in the simplest form  is called empirical formula.

It is not the same as structural formula and does not have any information regarding structure.It does not provide any information regarding structure of molecule as obtained in structural formula.

There are four types of chemical formula:

1)empirical formula

2) structural formula

3)condensed formula

4)molecular formula

Learn more about chemical formula,here:

https://brainly.com/question/29031056

#SPJ6

Anna is conducting an experiment to determine how weather affects cell phone reception. She is trying to decide the best way to conduct her experiment in order to collect meaningful data.

Answers

The question is incomplete, the complete question is;

Anna is conducting an experiment to determine how weather affects cell phone reception. She is trying to decide the best way to conduct her experiment in order to collect meaningful data. Which of the following experiments would help Anna collect the best data? A. Test different cell phones in different locations on days with clear weather. B. Test different cell phones in different locations on days with rainy weather. C. Test a cell phone's reception in one location with clear weather and in another location with rainy weather. D. Test a cell phone's reception in the exact same location under various atmospheric conditions.

Answer:

D. Test a cell phone's reception in the exact same location under various atmospheric conditions.

Explanation:

In this experiment that Anna intends to carry out, the independent variable is the atmospheric condition. The dependent variable must be the cell phone reception, it is expected to change with  atmospheric conditions.

In order to obtain valid results, other factors such as  such as type of cellphone and location (control variables) must be held constant so as to collect the best data.

What happens to brain cells when we sleep?

Answers

Answer:

What happens is...

Explanation:

Specifically, it allows your neurons, or nerve cells, to reorganize. When you sleep, your brain's glymphatic (waste clearance) system clears out waste from the central nervous system. It removes toxic byproducts from your brain, which build up throughout the day. This allows your brain to work well when you wake up.

Need help fast please!
Find the mass of 4.56 mols of LaPO4

Answers

Answer:

Mass = 1080.26 g

Explanation:

Given data:

Number of moles of LaPO₄ = 4.56mol

Mass in gram = ?

Solution:

Formula:

Number of moles = mass/molar mass

Molar mass of LaPO₄ = 236.9 g/mol

by putting values,

4.56 mol = mass/ 236.9 g/mol

Mass = 4.56 mol  × 236.9 g/mol

Mass = 1080.26 g

The reaction energy type that has a negative value at the end of the reaction is called: a Barothermic b Exothermic c Endothermic d Isothermic

Answers

Answer:

b) Exothermic

Explanation:

Exothermic reaction:

The type of reactions in which energy is released are called exothermic reactions.

In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.

For example:

Chemical equation:

C + O₂   →  CO₂

ΔH = -393 Kj/mol

it can be written as,

C + O₂   →  CO₂ + 393 Kj/mol

When 1000 C of charge is passed through CuSO4 solution, x g of copper is deposited. How much charge should be passed through the solution to deposit 5x g of copper?​

Answers

Number of charge = 5018 C

Further explanation

Given

1000 C of charge for x grams of copper

Required

Number of charge

Solution

Faraday's Law :

[tex]\tt W=\dfrac{e.i.t}{96500}\\\\W=\dfrac{e.Q}{96500}[/tex]

For 1000 C, W = x grams

[tex]\tt x=\dfrac{1000.e}{96500}=0.0104e[/tex]

For 5x grams :

[tex]\tt 5x=\dfrac{e.Q}{96500}\\\\5\times 0.0104e=\dfrac{e.Q}{96500}\\\\Q=\dfrac{96500\times 5\times 0.0104e}{e}=5018~C[/tex]

help me pleaseeee, ty if you doo :))

Answers

H2O because there are 2 H and only 1 O :)

This chemical equation represents a chemical reaction.
Na2CO3 + 2HCl - 2NaCl + CO2 + H20
Which chemical is a reactant in the reaction shown?
A. HCI
B. NaCl
C. CO2
D. H20

Answers

Answer:

A. HCl

Explanation:

on the left hand side we have reactants.

hope it helps!

Copper carbonate (CuCO3) reacts with hydrochloric acid (HCl) according to this equation:
CuCO3(s) + 2HCl(aq) → CuCl2(aq) + H2O(l) + CO2(g).

Which statement correctly describes the substances in this reaction?

A.
Exactly one product and two reactants are either liquid or dissolved in water.
B.
Exactly one of the reactants is in a water-based solution, but none of the products are.
C.
The reactants include both a liquid and a gas.
D.
Exactly one reactant is a solid, and exactly one product is a gas.
E.
The products include a solid, a liquid, and a gas.

Answers

Answer:

d

Explanation:

plato

Answer:

d

Explanation:

answer with correct significant figures (*no scientific notation): 847.3219 x 34.6 x 1.4560 =

Answers

Answer:

42686.04375

Explanation:

Multiply 847.3219 by 34.6 to get 29317.33774, then multiply this answer by 1.4560 to get the final answer which is 4286.04375.

What is the energy required to go from a solid to a liquid called?
A. The latent heat of fusion
B. The thermal energy of a substance
C. The latent heat of vaporization
D. The specific heat capacity

Answers

Answer:

enthalpy of fusion also called heat of fusion

A) would be the correct answer to this question

Based only on the distance between the valence electron and the nucleus, which atom has a stronger attraction between its nucleus and its valence electrons? How do you know? Please explain in at least 2 sentences.


lithium and sodium

Answers

Answer:

Lithium

Explanation:

Although sodium may seem like a viable answer because it has more protons (and thus a greater attractive force) in its nucleus, we need to take into account what "valence electrons" means. Valence electrons are, simply, electrons that are on the outermost electron shell of an atom. Sodium has an additional shell of electrons compared to lithium that are far away from the nucleus. Thus, lithium, which has valence electrons closer to its nucleus, would have a stronger attraction between its nucleus and its valence electrons.

Compare and contrast a thermodynamically stable compound and a kinetically stable compound at room temperature with respect to overall energy change, spontaneity with which decomposition occurs, and reaction rate.

Answers

Answer:

"im different"

Explanation:

Please help correct answers only please

Answers

Answer:

Empirical formula is C₅H₁₂O

Molecular formula = C₅H₁₂O

Explanation:

Given data:

Percentage of hydrogen =13.75%

Percentage of carbon = 68.11%

Percentage of oxygen = 18.15%

Empirical formula = ?

Solution:

Number of gram atoms of H = 13.75 / 1.01 = 13.6

Number of gram atoms of O = 18.15 / 16 = 1.13

Number of gram atoms of C = 68.11 / 12 = 5.68

Atomic ratio:

            C                      :      H               :         O

           5.68/1.13           :     13.6/1.13     :       1.13/1.13

            5                      :        12          :        1

C : H : O = 5 : 12 : 1

Empirical formula is C₅H₁₂O.

Molecular formula:

Molecular formula = n (empirical formula)

n = molar mass of compound / empirical formula mass

Empirical formula mass :

5×12 + 12×1.01 + 16×1 = 88.12 g/mol

n = 88.17/ 88.12

n = 1

Molecular formula = n (empirical formula)

Molecular formula = 1 (C₅H₁₂O)

Molecular formula = C₅H₁₂O

A wave on a lake has a wavelength of 5.0 M and a Frequency of 4 Hz. What is the speed of the wave in m/s?

Answers

Answer:

The appropriate speed will be "20 m/s".

Explanation:

The given values are:

Wavelength,

λ = 5.0 M

Frequency,

f = 4 Hz

Now,

The speed of the wave will be:

⇒ [tex]V=f\times \lambda[/tex]

On putting the values, we get

⇒     [tex]=4\times 5.0[/tex]

⇒     [tex]=20 \ m/s[/tex]

PLEASEEE HELP me on CHEMISTRY!! Will give brainliest!
Two students plan and carry out an investigation to determine if ionic or covalent bonds have stronger intermolecular forces. They check the following data.
a. identify the type of intramolecular bonds that are involved.
b. Which substance will have the stronger intermolecular forces?
c. Which properties allow you to predict the strength of the intermolecular forces?

Answers

Answer:

A Glucose C6H12O6 is a covalent compound while NaCl sodium chloride is a ionic compound.

B Stronger molecular forces are present in NaCl because ionic bond is stronger than covalent bond.

C melting point allow us to predict the strength of intermolecular forces

High melting point stronger molecular forces and vice versa.

Explanation:

The temperature of 25 g of water was raised from 10 oC to 60 oC. How many joules of heat was necessary to accomplish this?

Answers

Answer:

Hope this helps!

Explanation:

balance the following skeleton equations Mg+02---->MgO

Answers

Answer:  [tex]2Mg+O_2\rightarrow 2MgO[/tex]

Explanation:

Skeletal equations are defined as the equations in which formula are used to indicate the chemicals that are involved in a chemical reaction.

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

Thus the balanced chemical equation will be :

[tex]2Mg+O_2\rightarrow 2MgO[/tex]

When a pendulum swings, at which point is kinetic
energy highest:

Answers

Answer:

3

Explanation:

At which point is kinetic energy greatest

Answers

Answer:

x is wen

Explanation:

Answer:

I would say at point ''X''

ine element and compound with example.
What is symbol? Write its significance.
Define mixture. Write its types.
Write the difference between mixture and compound.
What is a chemical equation? What are the essentials of
chemical equation? What information is conveyed by
chemical equation? What are its limitations and how are they
removed?
What do you understand by balancing of a chemical equation
Why 'partial equation method' is considered to be better than
"hit and trial method'?
What information is​

Answers

Explanation:

an element is a substance which cannot be spilt upto two or more simple substances.For eg gold,silvera compound is the substance produced by the union of two or more elements in a definite proportion by weight .For eg water,carbon dioxideI dont knowA mixture is a substance formed by mixing two or more elements are compounds in any proportion by mass .Its types are:Hetregeneous mixture and homogeneous mixture.

the difference between mixture and compound is that a mixture is a substance formed by mixing two or more elements are compounds in any proportion by maths and compound is a substance produced by the union of two or more elements in a definite proportion by weight.chemical equation is defined as the symbolic representation of a chemical reaction

if hydrochloride tablets and eno combine what will the reaction​

Answers

answer is attached in the image below

Answer:

Hydrochloric Acid

Explanation:

The number of molecules in 48.0 grams of oxygen gas (O2) is...
O 6.02 x 1023
O 1.81 x 1024
O 1.20 x 1024
9.03 x 1023

Answers

Answer:

9.033 × 10²³ molecules

Explanation:

Given data:

Mass of oxygen = 48.0 g

Number of molecules = ?

Solution:

Number of moles of oxygen:

Number of moles = mass/molar mass

Number of moles = 48.0 g/ 32 g/mol

Number of moles = 1.5 mol

Avogadro number:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.  The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ molecules

1.5 mol  × 6.022 × 10²³ molecules  / 1mol

9.033 × 10²³ molecules

Na2S2O3 + AgBr NaBr + Na3ſAg(S203)2] What is
the mass of NaBr that will be produced from 42.7 g of AgBr?

Answers

Answer:

Mass of NaBr produced  = 23.67 g

Explanation:

Given data:

Mass of AgBr = 42.7 g

Mass of NaBr produced = ?

Solution:

Chemical equation:

2Na₂S₂O₃ + AgBr    →    NaBr + Na₃(Ag(S₂O₃)₂

Number of moles of AgBr:

Number of moles = mass/molar mass

Number of moles = 42.7 g/ 187.7 g/mol

Number of moles = 0.23 mol

now we will compare the moles of AgBr with NaBr.

             AgBr        :         NaBr

                1            :           1

              0.23       :         0.23

Mass of NaBr:

Mass = number of moles × molar mass

Mass = 0.23 mol × 102.89 g/mol

Mass = 23.67 g

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