Why are metals malleable?
A. Because their lattice energy is very high
B. Because they are made of atoms that have tightly held electrons
C. Because of their structure and uniform bonding in all directions
D. Because they reflect incoming photons

Answer: Potassium and fluorine

Explanation:

The two rows form bonds the easiest

Answer: #1

Explanation:

Answer:

The final temperature of the water when measuring the food sample is: The temperature of the water when the food sample has finished burning completely.

Explanation:

When measuring the food sample in energy and specific heat lab, it is pertinent to note that there is an initial temperature and even while still burning, the temperature gradually increases. But since we are dealing with final, temperature, what we need is basically the final temperature of the water when the food has finished burning. This is so because that's the final temperature of the water as once the food sample has finished burning and you turn off the heat source, the temperature will start to gradually reduce from then on.

Answer:

See the answer below

Explanation:

The slide could have broken due to the ramming of the objective (especially the high power objectives) into the slide on the stage of the microscope while trying to bring the object on the slide into focus.

It is recommended to start with the lowest objective while trying to focus a slide. Thereafter, the next higher objective can be switched to and the image brought into focus once again. This can be repeated until the desired magnification of the image is reached.

However, at higher objective powers, the coarse adjustment knob should be avoided to avoid the objectives touching/breaking the slide. Instead, the fine adjustment knob should be used.

Hence, the breaking of the slide in the illustration could have been due to the use of the coarse adjustment knob at higher objective powers and the ramming of the objective into the slide.

Answer:

Zamir walked

27

meters and Talia walked

19

meters.

Explanation:

27 and 19

Answer:

zamir:27  Talia:19

Explanation:

i got it right on my test :)

Answer:

[tex]m_{CO_2}=3.709gCO_2 \\\\m_{H_2O}=1.898gH_2O[/tex]

Explanation:

Hello.

In this case, since the molecular formula of the given alcohol is C₄H₁₀O (molar mass = 74.14 g/mol), we can write its combustion reaction as shown below:

[tex]C_4H_1_0O+6O_2\rightarrow 4CO_2+5H_2O[/tex]

Thus, since there is a 1:4 mole ratio with carbon dioxide (molar mass = 44..01 g/mol) and a 1:5 mole ratio with water (molar mass = 18.02 g/mol), we can compute the obtained masses as shown below:

[tex]m_{CO_2}=1.562gC_4H_1_0O*\frac{1mol}{74.14gC_4H_1_0O} *\frac{4molCO_2}{1molC_4H_1_0O} *\frac{44.01gCO_2}{1molCO_2}=3.709gCO_2 \\\\m_{H_2O}=1.562gC_4H_1_0O*\frac{1mol}{74.14gC_4H_1_0O} *\frac{5molH_2O}{1molC_4H_1_0O} *\frac{18.02gH_2O}{1molH_2O}=1.898gH_2O[/tex]

Best regards!

Answer:

Ne

Explanation:

It has the lowest density.

Neon has the lowest density since it has the smallest atomic size and the lowest atomic number.

The atomic density of an element refers to the number of atoms contained in an element per unit volume.

The size of an atom has an effect on atomic density. The size of an atom increases from left to right across the period and top to bottom down the group.

As such, on the periodic table, as we move from top to bottom down the group, the density of an atom increases.

The atomic element of the given elements are:

Therefore, we can conclude that Neon (Ne) will have the lowest density since it has the smallest atomic size and the lowest atomic number.

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Answer:

is used

Explanation:

The concentrations : 0.15 M

pH=11.21

The ionization of ammonia in water :

NH₃+H₂O⇒NH₄OH

NH₃+H₂O⇒NH₄⁺ + OH⁻

The concentrations of all species present in the solution = 0.15 M

Kb=1.8 x 10⁻⁵

M=0.15

[tex]\tt [OH^-]=\sqrt{Kb.M}\\\\(OH^-]=\sqrt{1.8\times 10^{-5}\times 0.15}\\\\(OH^-]=\sqrt{2.7\times 10^{-6}}=1.64\times 10^{-3}[/tex]

[tex]\tt pOH=-log[OH^-]\\\\pOH=3-log~1.64=2.79\\\\pH=14-2.79=11.21[/tex]

Answer:The formula of magnesium chloride is MgCl2 . The molar mass of MgCl2 is (24.30 + 2 × 35.45) g/mol=95.20 g/mol .

Explanation:

Answer: D

Explanation:

Hydropower

Answer:

Speed of light

Explanation:

The value 3.0 x 10⁸m/s is taken as the speed of light.

It is a constant.

Answer:

0.184 M

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

HCl + NaOH —> NaCl + H2O

From the balanced equation above, the following data were obtained:

Mole ratio of the acid, HCl (nA) = 1

Mole ratio of the base, NaOH (nB) = 1

Next, the data obtained from the question. This includes:

Volume of the base, NaOH (Vb) = 31.7 mL Molarity of the base, NaOH (Mb) = 0.145 M

Volume of the acid, HCl (Va) = 25.0 mL

Molarity of the acid, HCl (Ma) =?

Finally, we shall determine the molarity of the acid (HCl) as shown below:

MaVa /MbVb = nA/nB

Ma × 25 / 0.145 × 31.7 = 1

Cross multiply

Ma × 25 = 0.145 × 31.7

Ma × 25 = 4.5965

Divide both side by 25

Ma = 4.5965 / 25

Ma = 0.184 M

Therefore, the molarity of the acid (HCl) is 0.184 M

Answer:

0.0035M

Explanation:

Given parameters

Volume of HCl  = 100mL  = 0.1L

Volume of LiOH = 46.9mL  = 0.0469L

Molarity of LiOH = 0.75M

Unknown:

Concentration of hydrochloric acid = ?

Solution:

The reaction equation is given as;

         HCl   +  LiOH →   LiCl  + H₂O

Let us find the number of moles of the given specie which is LiOH;

   Number of moles  = molarity x volume;

    Number of moles of LiOH = 0.75 x0.0469  = 0.035moles

From the balanced reaction equation;

        1 mole of LiOH combines with 1 mole of HCl

     0.035mole of LiOH will require 0.035mole of HCl

Concentration of HCl = [tex]\frac{number of moles of HCl}{volume of HCl}[/tex]  

 Concentration of HCl  = [tex]\frac{0.035}{0.1}[/tex]   = 0.0035M

Answer:

The third one

Explanation:

Answer:

The answer is B

Explanation:

I had the same question and I chose B and it was correct.

Answer:

B. Carbon needs more than just three bonds to reach a noble gas

Explanation:

PLATO ANSWER

PLATO EXPLANATION-

Each hydrogen atom can make only one bond, but a carbon atom needs four bonds to be stable. Therefore, three hydrogen atoms are not enough for the carbon atom to make four bonds.

Answer:

The wavelength of the energy that needs to be absorbed  = 52.36 nm

Explanation:

For this study;

Let consider the Rydgberg equation from Bohr's theory of atomic model:

i.e.

[tex]\dfrac{1}{\lambda} = R_H (Z^*)^2( \dfrac{1}{n_1^2}-\dfrac{1}{n_2^2})[/tex]

where

Z* = effective nuclear charge of atom = Z - σ = 6

n₁ = lower orbit = 3

n₂ = higher orbit = 4

[tex]R_H[/tex] = Rydyberg constant = 1.09 × 10⁷ m⁻¹

λ = wave length of the light absorbed

∴

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(6)^2( \dfrac{1}{3^2}-\dfrac{1}{4^2})[/tex]

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(36)( \dfrac{1}{9}-\dfrac{1}{16})[/tex]

[tex]\dfrac{1}{\lambda} = 392400000\times0.0486111111[/tex]

[tex]\dfrac{1}{\lambda} =19075000[/tex]

[tex]\lambda = \dfrac{1}{19075000}[/tex]

[tex]\lambda = \dfrac{1}{1.91\times 10^7 \ m^{-1}}[/tex]

[tex]\lambda = 5.236 \times 10^{-8} m[/tex]

[tex]\lambda = 52.36 \times 10^{-9} m[/tex]

[tex]\lambda = 52.36\ n m[/tex]

Therefore, the wavelength of the energy that needs to be absorbed  = 52.36 nm

Answer:

1.99 x 10⁻¹⁸J

Explanation:

Given parameters:

Frequency of the wave  = 3 x 10¹⁵Hz

Unknown:

Energy of the photon  = ?

Solution:

To solve this problem, we use the expression below;

     E  = hf

Where E is the energy, h is the Planck's constant and f is the frequency

Now insert the parameters and solve for E;

     E  = 6.63 x 10⁻³⁴ x 3 x 10¹⁵ = 19.9 x 10⁻¹⁹J or 1.99 x 10⁻¹⁸J

Hydrogen can only form single covalent bonds when forming molecular compounds. Therefore, option B is correct.

A covalent bond is a type of chemical bond formed between two or more atoms in which electrons are shared between them. Covalent bonds usually occur between nonmetal atoms and are formed by the sharing of valence electrons.

Hydrogen can only form a single covalent bond because it has only one valence electron and needs one more electron to complete its valence shell, making it stable.

Nitrogen can form triple covalent bonds, carbon can form multiple covalent bonds, and oxygen can form double covalent bonds in molecular compounds.

Thus, option B is correct.

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Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\ [/tex]

From the question we have

[tex]n = \frac{4.5 \times {10}^{24} }{6.02 \times {10}^{23} } \\ = 7.475083056...[/tex]

We have the final answer as

Hope this helps you

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b competition .

hope it helps u

Answer:

3.01 x 10²³ molecules

Explanation:

Given parameters:

Number of moles of oxygen atoms  = 6.17moles

Unknown:

Number of molecule of tin(IV) nitrate  = ?

Solution:

To solve this problem, let us write the formula of tin (IV) nitrate;

              N₄O₁₂Sn

Now,

       12 moles of Oxygen can be found in 1 mole of  N₄O₁₂Sn

      6.17 moles of oxygen will be found in [tex]\frac{6.17}{12}[/tex]   = 0.5mole of  N₄O₁₂Sn

So;

       1 mole of a substance contains 6.02 x 10²³ molecules

  0.5 mole of N₄O₁₂Sn will contain 0.5 x 6.02 x 10²³ = 3.01 x 10²³ molecules

Answer:

6.022×10²³ atoms of K

Explanation:

Given data:

Mass of KClO₃ = 122.5 g

Number of atoms of K = ?

Solution:

First of all we will calculate the number of moles of KClO₃ .

Number of moles = mass/molar mass

Number of moles = 122.5 g/ 122.5 g/mol

Number of moles = 1 mol

One mole of KClO₃ have 1 mole of K atoms.

Number of atoms of K:

1 mole = 6.022×10²³ atoms of K

Thus in 122.5 g of KClO₃  6.022×10²³ atoms of K are present.

Answer:

Explanation:

in a combustion of ethane 2 moles of ethane react with 7 moles of O2

now no of moles in 54 gram of O2=mass/ molar mass

moles =54/32=1.7 moles

if 7 moles of O2 required 2 moles of ethane then 1.7 mole required=?

7 moles of O2=2 moles of C2H6

1.7 moles of O2=1.7*2/7=0.5 moles of C2H6

0.5 moles of C2H6 contain how much grams=?

mass= moles*molar mass=0.5*30=15

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(NH4)2 SO4

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Answer:

The answer is "1 and 4 polygons were similar".

Explanation:

In the given question, in both figures 1 and 4, it's measure angle were 10, 60, 110. In figure number 4, its angle is 10, 60, and on the third side, its value is equal to 110, which is (180 - 70).

I'll see what I can do here...

1) Nonmetal

2) Calcium (Ca), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table.

3) Hafnium

4) 204.3833 u

5) Not sure what you're asking, but oble gas, any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table. The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og)

6) The metalloids; boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At)

7) The Actinide series contains elements with atomic numbers 89 to 103 and is the third group in the periodic table.

8) 33

9) 88

10) 30

Hope this helps!

The work energy of this process : 2337.298 J

The laws of thermodynamics 1 state that: energy can be changed but cannot be destroyed or created  

ΔU=Q-W

Q=m.c.Δt

[tex]\tt Q=8.85\times 2.650\times 63.2=1482.198~J[/tex]

the work (W) :

[tex]\tt W=Q-\Delta U\\\\W=1482.198-(-855.1)=2337.298~J[/tex]

Answer:

100 mL of Na2CO3

Explanation:

We'll begin by calculating the number of mole in 1 g of CaCO3. This can be obtained as follow:

Mass of CaCO3 = 1 g

Molar mass of CaCO3 = 100.09 g/mol

Mole of CaCO3 =?

Mole = mass /Molar mass

Mole of CaCO3 = 1/100.09

Mole of CaCO3 = 0.01 mole

Next, we shall determine the number of mole of Na2CO3 needed to produce 0.01 mole of CaCO3.

This is illustrated below:

Na2CO3 + CaCl2 —> 2NaCl + CaCO3

From the balanced equation above,

1 mole of Na2CO3 reacted to produce 1 mole of CaCO3.

Therefore, 0.01 mole of Na2CO3 will also react to produce 0.01 mole of CaCO3.

Next, we shall determine the volume of Na2CO3 needed for the reaction as illustrated below:

Mole of Na2CO3 = 0.01 mole

Molarity of Na2CO3 = 0.1 M

Volume of Na2CO3 solution needed =?

Molarity = mole /Volume

0.1 = 0.01 / volume of Na2CO3

Cross multiply

0.1 × volume of Na2CO3 = 0.01

Divide both side by 0.1

Volume of Na2CO3 = 0.01 / 0.1

Volume of Na2CO3 = 0.1 L

Finally, we shall convert 0.1 L to millilitres (mL). This can be obtained as follow:

1 L = 1000 mL

Therefore,

0.1 L = 0.1 L × 1000 mL / 1 L

0.1 L = 100 mL

Thus, 0.1 L is equivalent to 100 mL.

Therefore, 100 mL of Na2CO3 is needed for the reaction.

The volume of sodium carbonate used in the given reaction is 0.1 liter or 100mL.

Volume of the solution will be calculated by using the molarity as:

M = n/V, where

n is the moles of solute and this can be calculated as:

n = W/M , where

W = given or required mass

M = molar mass

Given chemical reaction is:
Na₂CO₃ + CaCl₂ → CaCO₃ + 2NaCl

Moles of 1g of CaCO₃ = 1g/100g/mole = 0.01 moles

From the stoichiometry of the reaction, it is clear that same moles of CaCO₃ produced by same moles of used Na₂CO₃.

0.01 moles of CaCO₃ = produced by 0.01 moles of Na₂CO₃

Now we calculate the volume of 0.01 moles and 0.100M of Na₂CO₃ as:

V = n/M

V= 0.01/0.100 = 0.1L or 100mL

Hence 0.1 L is the required volume.

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