1. Which of the following is not among the first twenty elements? A. Chlorine B. Beryllium C. Iron D. Calcium 2. The number of atoms in one mole of an element is referred to as A. molecularity B. chemical symbol C. atomicity D. chemical element 3. What is the chemical symbol of Aluminum? A. AL B. Al C. aL D. al. 4. Which of the following is a heterogeneous mixture? A. Soft drink B. Air C. Flood C. Solution salt 5. Which of the following is false about mixtures? A. They can easily be separated by Chemical method B. They are not represented by chemical formula C. They can be homogenous or heterogeneous D. The constituents are physically combined 6. Which of the following elements is diatomic? A. Sodium B. Potassium C. Helium D. Oxygen 7. A diatomic element has ___________ number of atoms in one molecule of its element. A. one. B. two. C. three. D. four. 8. Which of the following is an example of a colloidal solution? A. Chalk in water B. Sand in water C. Sugar solution D. Solution of eggwhite 9. A mixture whose constituents are uniformly mixed is referred to as a A. homogeneous mixture B. suspension C. heterogeneous mixture D. colloidal solution 10. _____________ is a force that opposes motion when two surfaces are in contact with each other. A. Movement B. Pressure C. Friction D. gravity 11. _____________ is a substance, which cannot be split or broken down into any simpler form by an ordinary chemical process. A. Mixture B. Element C. Compound D. Metals. 12. Alloys are best classified as A. elements B. compounds C. mixtures D. non-metals 13. A type of force which occurs when a body moves constantly over another body is the _______ A. static force B. dynamic force C. magnetic force D. frictional force. 14. Which of the following is NOT a characteristic of friction? A. The ratio of the frictional force and the normal reaction is constant. B. The frictional force is always equal to the force applied through weight. C. Static frictional force is independent of the surface area in contact. D. Friction supports motion. 15. Use of ball or roller bearing on a turning wheel of a machine A. can cause wear and tear of the wheel B. reduces friction between the wheel and the body parts of the machine C. decreases the efficiency of the machine. D. hinders the productivity of the machine. 16. Another way of reducing friction is by A. painting B. alloying C. oiling D. braising 17. A block of wood weighs 4N lies on a horizontal table. Calculate the frictional force between the table and the wood if the coefficient of the static friction is 0.5. A. 1.0N B. 0.2N C. 2.0N D. 0.4N 18. A body of mass 2kg was moved uniformly by a force of 15N, if acceleration due to gravity is 15m/s, determine the coefficient of dynamic friction. A. 0.75 B. 1.5 C. 0.5 D. 1.75 19. The symbol for Beryllium is A. B. B. Be C. Bl D. Bm 20. K is the symbol of A. Calcium B. Chromium C. Potassium D. Krypton

Answers

Answer 1

Answer:

c. iron

Explanation:

iron's atomic number is 26


Related Questions

Why do chemical reactions happen?

Answers

Answer:

Chemical reactions happen when two or more molecules interact and the molecules change.

Explanation:

Bonds between atoms are broken and created to form new molecules. That's it.

// have a great day //


Rubidium will react with oxygen in which of the following formulas?

RbO
RbO2
Rb2O
Rb3O2

Answers

Answer:

C-Rb20

Explanation:

The chemical formula for Rubidium oxide is Rb20.

Hope this helps!

Which instrument would be used to measure
the mass of a small stone?
I
1. graduated cylinder
2. Celsius thermometer
3. triple-beam balance
4. metric ruler

Answers

Answer:

3. Triple Beam Balance

Explanation:

A triple beam will be most suitable for measuring the mass of a small stone because it is very accurate, and has a reading error of +/- 0.05 gram.

You’re trying to remove dissolved iron from a solution. The theoretical yield for a reaction between sodium sulfide and iron(III) bromide is 0.721 kilogram of solid iron(II) sulfide. When you carried out the reaction, you got 530.0 grams. What is the percent yield?

FREEBE HAVENT SEEN THIS QUESTION YET


ANSWER!!!
The percent yield of the reaction is 73.5%

Answers

Answer:

73.5%

Explanation:

Step 1:

Data obtained from the question.

Theoretical yield = 0.721Kg

Actual yield = 530g

Percentage yield =..?

Step 2:

Conversion of 0.721Kg to grams. This is illustrated below:

1Kg = 1000g

Therefore, 0.721Kg = 0.721 x 1000 = 721g

Step 3:

Determination of the percentage yield.

The percentage yield can be obtained by using the following formula:

Percentage yield = Actual yield /Theoretical yield x 100

Percentage yield = 530/721 x 100

Percentage yield = 73.5%

Therefore, the percentage yield is 73.5%

Answer:

73.5%

Explanation:

plato

In the reaction AgNO3(aq) + NaCl(aq) –
NaNO3(aq) + AgCl(s), the reactants
(1) gain electrons only
(2) lose electrons only
(3) both gain and lose electrons
(4) neither gain nor lose electrons

Answers

(4); this is a double replacement reaction

The alcohol family has properties similar to_____. HCl H2O NaCl H2SO4

Answers

Answer: H2O

Explanation: The alcohol family has properties similar to H2O.

Answer:

H2O

Explanation:

use the periodic table to select the element that best fits each of the following descriptions. which element below has properties of both metals and nonmetals?
zinc aluminum copper boron

Answers

Answer: Boron is the element which has properties of both metals and nonmetals.

Explanation:

Metals are defined as the elements which loose electrons to attain stable electronic configuration. They attain positive charge and form cation. Example: Zinc (Zn), Aluminium (Al) , copper (Cu)

Non-metals are defined as the elements which gain electrons to attain stable electronic configuration. They attain negative charge and form anion. Example: Chlorine (Cl) , Sulphur (S)

Metalloids are defined as the elements which show properties of both metals and non-metals. There are 7 metalloids in the periodic table. They are Boron (B) , Silicon (Si) , Germanium (Ge) , Arsenic (As) ,  Antimony (Sb), Tellurium (Te) and Polonium (Po).

Thus boron is the element which has properties of both metals and nonmetals.

Answer:

The answer is A boron!!!!!!

Explanation:

i took the quiz on ed

Solve for P2 when P1 = 2.0 atm V1 = 8.0 L and V2 = 32 L
This is a Boyle’s law has problem

Answers

P1/V1=P2/V2
2/8=x/32
X=2 multiplied by 32 divide by 8
P2=8atm

What is the concentration of a solution with a volume of 660L that contains 33.4g of AlCO3?

Answers

Answer:

The concentration of the solution is 5.8168 × [tex]10^{-4}[/tex] mol.[tex]dm^{-3}[/tex]

Explanation:

Here, we want to calculate the concentration of the solution.

The unit of this is mol/dm^3

So the first thing to do here is to calculate the number of moles of the solute present, which is the number of moles of AlCO3

The number of moles = mass/molar mass

molar mass of AlCO3 = 27 + 12 + 3(16)  = 27 + 12 + 48 = 87g/mol

Number of moles = 33.4/87 = 0.384 moles

This 0.384 moles is present in 660 L

x moles will be present in 1 dm^3

Recall 1 dm^3 = 1L

x * 660 = 0.384 * 1

x = 0.384/660 = 0.00058168 = 5.8168 * 10^-4 mol/dm^3

What is the correct prefix for 6?

Answers

Answer:

hex-

Explanation:

Prefix Prefix meaning Sample word

hex-           6                                  hexapod: having six legs, an insect, for      

                                                                   example.

Answer:

Hex-

Explanation:

Which statement about electric charge is true? A. Electric charge is created by an electric current. B. Electric charge influences whether objects attract or repel one another. C. Electric charge tends to be neutral in the nuclei of atoms. D. Electric charge will increase with an increase in temperature.

Answers

Answer:

A

Explanation:

Answer:

Electrical forces can act from a distance

Explanation:

A. Because electrical forces act at a distance, charged objects brought near a neutral object will cause electrons on the neutral object to rearrange their position

Examine the reaction. NH4OH(aq) →H2O(l) + NH3(g)
What coefficients will balance the equation?
A) 1, 1, 1
B) 3, 3, 4
C) 2, 1, 2
D) 1, 2, 2

Answers

Answer:  A.  1,1,1

Explanation:

The coefficients that will balance the equation; NH4OH(aq) →H2O(l) + NH3(g), is 1, 1, 1, because it proves the total number of atoms of each element on the LHS and RHS of the equation are equal, hence balanced.

LHS          RHS

N = 1            1

H = 5          5

O = 1            1

state true or false soil contains only in organic materials​

Answers

Answer:

false

Explanation:

the soil contain: organic materials, and inorganic materials

. Se dispone de una muestra impura de aluminio de 50g. Se hace reaccionar con sulfú rico para encontrar su riqueza. Hallar la riqueza sabiendo que se obtienen 28g de sal.

Answers

Answer:

9.32% de riqueza de Al en la muestra

Explanation:

La reacción de aluminio (Al) con ácido sulfúrico (H₂SO₄) es:

2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂

Dos moles de aluminio reaccionan con 3 moles de ácido sulfúrico para producir una mol de sulfato de aluminio (Sal).

Las moles de 28g de sulfato de aluminio (Masa molar: 324.15g) son:

28g ₓ (1 mol / 324.15) = 0.0864 moles de Al₂(SO₄)₃

Así, las moles de aluminio que reaccionaron fueron:

0.0864 moles de Al₂(SO₄)₃ ₓ ( 2 moles Al / 1 mol Al₂(SO₄)₃) =

0.1728 moles de Al. En gramos (Masa atómica: 26.98g/mol):

0.1728 moles Al ₓ (26.98g / mol) = 4.66g de aluminio.

Así, la riqueza de la muestra es:

4.66g Al / 50g muestra ₓ100 = 9.32% de riqueza de Al en la muestra

Which compound is a saturated hydrocarbon?
A) 2-pentanone B) 2-pentene C) pentane D) pentanal

Answers

The answer is the first one because it’s a compound of two words separate when you say it :) hope this helps !

someone tell me how to balance the equation by hit and trial method...​

Answers

Answer:

1. 3H2S + 2HNO3 -----> 2NO + 4H2O + 3S

Explanation:

H2S + HNO3 ----->  NO + H2O + S

There are 3 O's on left and  only 2 on right so  put 2 before NO:

H2S + HNO3 ----> 2NO + H2O + S

Now we have 2 N's on left so put 2 before HNO3:

H2S + 2HNO3 -----> 2NO + H2O + S

4 H's on the left so

H2S + 2HNO3 -----> 2NO + 2H2O + S

That makes 6 O's on left so  we write

H2S + 2HNO3 ----> 2NO + 4H2O + S

Now there 8 H's on the right but only 4 on the right so we adjust H2S and S:

3H2S + 2HNO3 -----> 2NO + 4H2O + 3S

Now it balances!

Basically you 'play around' with the  quantities of each element in this way.


The major difference between a 1s orbital and a 2s orbital is that

The 2s orbital has a slightly different shape.
The 2s orbital is at a higher energy level.
The 2s orbital can hold more electrons.
The 1s orbital can have only one electron.

Answers

Answer:

The 2s orbital is at a higher energy level.

Explanation:

1s and 2s are the sub-orbitals that are located in an atom. They are nearest to the nucleus and are found on the s sub-orbital. The difference between 1s and 2s is the difference in their level of energy. 1s has low energy as compared to 2s. 1s orbital has the lowest energy because it is located closed to the nucleus. 2s orbital has higher energy than 1s because it's orbit is larger than 1s.

In this equation, what should be the coefficients of the reactants and products? I2 + O2 → I4O9

Answers

Answer:

4 i2  + 9 O2 --> 2 i4O9

Explanation:

4 i2 + 9 O2 => 2 i4O9

what is the substitution reaction
plzz answer ​

Answers

Answer:

it is a reaction whereby one or more reactants of the reaction are changed or replaced .

What is the volume occupied by 3.00 mol of hydrogen gas at STP? *

Answers

Answer: V=67.2 L

Explanation:

For this problem we will need to use the Ideal Gas Law.

Ideal Gas Law: PV=nRT

P=1.00 atm (STP)

V=?

n=3.00 mol

R=0.08206Latm/Kmol

T=273.15 K (STP)

To find V, we would manipulate the equation to V=nRT/P

[tex]V=\frac{(3.00 mol)(0.08206Latm/Kmol)(273.15K)}{1.00 atm}[/tex]

[tex]V=67.244 L[/tex]

With significan figures, our answer is V=67.2 L.

What is the name of CH3CH(OH)CH2CH2CH3?

Answers

Answer: 2-butanol

Explanation: I looked it up, I really don’t know how trustworthy my source was. (not Wikipedia)

Explain why the boiling point of H2S with relative molecular mass 34 is lower than that of H2O with relative molecular mass 18​

Answers

Answer and Explanation:

In H2O molecules, due to formation of intermolecular hydrogen bonds, there is molecular association. Large amount of energy is required to break these intermolecular hydrogen bonds. Intermolecular hydrogen bonding is not possible in H2S. Hence, its boiling point is lower and is a gas.

Balance the following reaction. A coefficient of "1" is understood. Choose option "blank" for the correct
answer if the coefficient is "1."
CS2+
CI,
* CCI +
s2Cl2

Answers

Answer: [tex]CS_2+3Cl_2\rightarrow CCl_4+S_2Cl_2[/tex]

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products formed must be equal to the mass of reactants taken.

In order to get the same mass on both sides, the atoms of each element must be balanced on both sides of the chemical equation.

The given chemical equation is:

[tex]CS_2+Cl_2\rightarrow CCl_4+S_2Cl_2[/tex]

The balanced chemical equation is:

[tex]CS_2+3Cl_2\rightarrow CCl_4+S_2Cl_2[/tex]

Answer:

blank, 3, blank, blank

Explanation:

name two gases which are supplied in compressed form in homes and hospitals​

Answers

Explanation:

lpg and oxygen are two gases which are supplied in compressed form in homes and hospitals

Answer:

lpg and oxygen

they are the two gases which are supplied in either a gas form or any other medical forms in homes and hospitals to look after the ill patients or family members

35. The hydrocarbon formed during electrolysis of potassium maleate is
a)methane
b)ethane
c)ethene
d)ethyne

Answers

Answer:

methane

Explanation:

9. Determine the number of protons, neutrons, and electrons in one 'H' ion. Explain how you found your
answer.​

Answers

Answer:

'H' ion has only one proton and do not have any electron and neutron.

Explanation:

Hydrogen atom has only one electron and one proton and when it loses that electron, hydrogen ion (H+) is formed which is positively charged (charge of +1) and referred as a proton.

So, hydrogen ion do not left with any electrons or have zero electrons.

Hydrogen (H) atom do not have any neutrons in its tiny nucleus, so hydrogen ion (H+) also do not have neutrons.

Hence, 'H' ion (H+) has only proton and zero electron and neutron.

LIST TWO SUBSTANCE THAT CAN BE USED TO (i)REDUCE THE ACIDITY OF A SUBSTANCE

Answers

Answer:

An acidic substance is any substance with a pH of less than 7, the smaller the number the more acidic it is. ... An acid is a substance that donates hydrogen ions. Because of this, when an acid is dissolved in water, the balance between hydrogen ions and hydroxide ions is shifted.

Explanation:

Carbon monoxide reacts with oxygen to produce carbon
dioxide. The given reaction is an example of

Answers

oxidation

CO + O = C

as u can see, the oxgyen has been reduced

The specific heat capacity of methane gas is 2.20 J/g°C. How many joules of heat are needed to raise the temperature of 5.00 g of methane from 22.0°C to 57.0°C?

a-79.5 J

b-385J

c-869 J

d-0.0126 J

Answers

Answer:

b - 385 j

Explanation:

Four satellites are in orbit around the Earth. The heights of their four orbits
are identical. The masses of the four satellites are given in the table. For
which satellite is the gravitational pull of Earth the strongest?
Satellite
Mass (kg)
A
500
B
400
700
600
O A. Satellite A
O B. Satellite B
O C. Satellite
O D. Satellite D

Answers

Answer:

Option C. Satellite C.

Explanation:

The gravitational pull of the earth talls about the weight of an object.

To know which of them has the greatest gravitational pull, let us determine the weight of each satellite.

For satellite A:

Mass = 500Kg

Acceleration due to gravity (g) = 9.8m/s²

Weight (W) =.?

Weight (W) = mass (m) x Acceleration due to gravity (g)

W = m x g

W = 500 x 9.8

W = 4900N

For satellite B:

Mass = 400Kg

Acceleration due to gravity (g) = 9.8m/s²

Weight (W) =.?

W = m x g

W = 400 x 9.8

W = 3920N

For satellite C:

Mass = 700Kg

Acceleration due to gravity (g) = 9.8m/s²

Weight (W) =.?

W = m x g

W = 700 x 9.8

W = 6860N

For satellite D:

Mass = 600Kg

Acceleration due to gravity (g) = 9.8m/s²

Weight (W) =.?

W = m x g

W = 600 x 9.8

W = 5880N

Satellite >> Mass >>> Gravitational pull

A >>>>>>>> 500Kg >> 4900N

B >>>>>>>> 400Kg >> 3920N

C >>>>>>>> 700Kg >> 6860N

D >>>>>>>> 600Kg >> 5880N

From the above calculations we can see that satellite C has the greatest gravitational pull.

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