Pls help with science

Answer:

d. It maintains the distances between planets.

Explanation:

Answer:

Of course the answer is gold

Explanation:

Gold is used for making jewellery and not aluminium,iron or copper

Answer:

copper or gold.

Explanation:

Copper is also a good material for accessories. Even in the ancient times, those who can’t afford gold jewelry wear copper jewelry instead. It offers design flexibility too due to its high ductility.

Answer: pretty sure its 0.214 moles * 40.3g/mole = 8.6g (2 sig figs) of MgO, and

0.035 moles * 40.3g/mole = 1.4g of MgO

Explanation:

Answer:

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Answer:

H, Na, N

Explanation:

Answer:

H, NA, N

Explanation

Answer:

The anomalous expansion of water refers to the fact that water, unlike most substances, expands when it freezes. The density of water increases as temperature decreases, but reaches a maximum at 4 degrees C then begins to expand. The significance of this is that ice is less dense than water so it floats in water.

This is of major biological importance. Lakes, ponds and streams freeze from the top down instead of from the bottom.

There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Therefore, the correct option is option C.

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

An ionic compound is a metal and nonmetal combined compound.  Ionic compound are very hard. They have high melting and boiling point because of strong ion bond.

Since phosphorus is a nonmetal, we need a metal. Out of given option the only element that is metal is Magnesium while others are non metal.

Therefore, the correct option is option C.

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Answer:

devide by avogadro constant 6.02*10^23

Explanation:

Answer:

30.26 °C

Explanation:

From the question,

Q = cm(t₂-t₁)................ Equation 1

Where Q = Heat, c = specific heat capacity of Cu, m = mass of Cu, t₁ = Initial temperature, t₂ = Final temperature.

Given: Q = 1000 J, c = 0.39 J/g.°C, t₁ = 20°C, m = 250 g

Substitute into equation 1 and solve for t₂

1000 = 250×0.39(t₂-20)

250×0.39(t₂-20) = 1000

97.5(t₂-20) = 1000

(t₂-20) = 1000/97.6

(t₂-20) = 10.26

t₂ = 10.26+20

t₂ = 30.26 °C

hope it helps :-). good morning.

Answer:

Nerve cells in the hypothalamus make chemicals that control the release of hormones secreted from the pituitary gland. The hypothalamus gathers information sensed by the brain (such as the surrounding temperature, light exposure, and feelings) and sends it to the pituitary.

Explanation:

Answer:

Metals are found to the left of the zigzag line on the periodic table. B. Nonmetals Nonmetals are found to the right of the zigzag line on the periodic table.

Explanation:

Answer:

Wetlands prevent flooding by temporarily storing and slowly releasing stormwater. Wetlands also reduce water flow, thus allowing sediments and associated pollutants to settle out. Beneficial microor- ganisms (called biofilm) live on wetland plants and process some forms of pollution.

Explanation:

Answer:

46.9 atm

Explanation:

Applying Van der waals equation

P = [nRT/(V-nb)]- (an²/V²)............... Equation 1

Where P = pressure, T = temperature, n = number of moles, V = volume, R = Universal constant, a and b = gas constant

Given: n = 20 moles, R = 0.08205 L.atm/mol.K, T = 273 K, V = 10.0 L, a = 0.0341 atm.L²/mol², b = 0.0237L/mol

Substitute these values into equation 1

P = [(20×0.08205×273)/(10-20×0.0237)]-(0.0341×20²/10²)

P = (447.993/9.526)-0.1364

P = 47.028-0.1364

P = 46.9 atm

Answer:

Scientist 3

Explanation:

Answer:

D. 1.0 x 10-8.43

Explanation:

The pH is an unit of concentration in chemistry used to determine the acidity -or basicity- of a particular solution. Is used in quality control to determine the security of a product for consumers.

The equation is:

pH = -log [H₃O⁺]

As pH = 8.43:

8.43 = -log [H₃O⁺]

10^-8.43 = [H₃O⁺]

1.0x10 -8.43 = [H₃O⁺]

Right option is:

Answer:

nope its a myth don't worry :)

Answer:

não sei ainda mas acho que e A

Answer:

e c f

Explanation:

read the question and it tells you how to do it and I can get you to help

The first to dissolve is the solute in tank B. The amount of a substance that dissolves in a specific solvent concentration at a specific temperature is known as its solubility.

The introduction of a solute to a solvent is the first stage in the dissolving process. The molecules of these two substances begin to interact, causing the solute molecules to disperse and become encircled by solvent molecules.

In water, salt, sugar, and coffee all dissolve. They disintegrate quickly. They typically dissolve more rapidly and completely in hot or warm water. Even very hot water won't be able to dissolve sand or pepper.

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Answer:

The answer would be 0.65625

Answer:

0.208333 M

Explanation:

M2=M1V1/V2=(0.25 M)(125mL)/(125mL+25 mL)= 0.208333 M

Answer:

That is, water has a high heat of vaporization, the amount of energy needed to change one gram of a liquid substance to a gas at constant temperature. Wate

Explanation:

Answer:

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Explanation:

Answer:

Because of the electronegativity difference C-O (covalent) and Ca-O (ionic) bonds have.

Explanation:

Hello there!

In this case, in order to understand the polarity of this compound, calcium carbonate, it firstly necessary that it is comes from the definition of electronegativity, as a property defining the capacity to attract electrons from another atom; thus, since the electronegativities of calcium, carbon an oxygen are 1.0, 2.55 and 3.44, it is possible to realize this compound has O-Ca and O-C bonds according to its Lewis dot structure. In such a way, we calculate the difference electronegativity for these two bonds:

[tex]\Delta E_{O-Ca}=3.44-1.0 = 2.44\\\\\Delta E_{O-C}=3.44-2.55=0.89[/tex]

Thus, since 2.44 accounts for an ionic bond and 0.89 for a covalent one, we bear out the given statement in the question.

Answer:

3.6mol

Explanation:

The balanced chemical equation of this reaction is given as follows:

Ni + 2HF → NiF2 + H2

Based on the above equation, 2 moles of HF will react to produce 1 mole of NiF2.

According to this question, to make 174 grams of NiF2, we find the number of moles of HF required. However, we first convert the mass value of NiF2 to mole value using;

mole = mass/molar mass

Molar mass of NiF2 = 58.7 + 19(2)

= 58.7 + 38

= 96.7g/mol

mole = 174/96.7

mole = 1.799mol of NiF2

Hence, if 2 moles of HF will react to produce 1 mole of NiF2.

- 1.799mol of NiF2 will require (1.799 × 2) = 3.598

= 3.6mol of HF.

Answer:

A) chlorine

Explanation:

To solve this question we can use:

PV = nRT

In order to solve the moles of the gas. With the moles and the mass we can find the molar mass of the gas to have an idea of its identy:

PV = nRT

PV / RT = n

Where P is pressure: 603mmHg * (1atm / 760mmHg) = 0.7934atm

V = 100mL = 0.100L

R is gas constant = 0.082atmL/molK

T is absolute temperature = 14°C + 273.15 = 287.15K

0.7934atm*0.100L / 0.082atmL/molK*287.15K = n

3.37x10⁻³ moles of the gas

In 0.239g. The molar mass is:

0.239g / 3.37x10⁻³ moles = 70.9g/mol

The gas with this molar mass is Chlorine, Cl₂:

Answer:

I believe it is hydrogen for the first and methane for the second.

Explanation:

Answer to 8: The most dangerous or harmful gas to humans in the atmosphere would be carbon dioxide. But reserchers have found that methane levels in ancient air samples and found that scientists have been vastly underestimating the amount of methane humans are emitting into the atmosphere via fossil fuels.

Answer to 7: The type of gases present are as critical to density as elevation and gravity, and all are interrelated. Certain atmospheric gases will create thick atmospheres. For example, atmospheres with abundant hydrogen tend to be thicker as gases will combine with hydrogen for greater mass.

Hope this helps!

Answer:

Explanation:

Step 1

The question is based on the concept of PH and pOH calculations.

pH is defined as negative logarithmic of hydronium Ion concentration.

while pOH is defined as negative logarithmic of hydroxide ion concentration of the solution.

Step 2

[H+] = 7.7*10-7  M  

pH = -log[H+]  

    = -log ( 7.7*10-7 )

     = 6.12

Step 3

pOH = 14 - pH

   = 14 - 6.11

  = 7.89