Teresa has taken three tests worth 100 points each. Her scores are 85, 93, and 88. She has one test left to take.

To get an average score of 90, what must the sum of all her test scores be?
a.
400
c.
600
b.
360
d.
300

Answer:

The heat flow into Earth's atmosphere varies as the Sun rises and sets, gradually increasing during the day and falling to zero at night.

Explanation:

Heat radiates from the ground into the lower atmosphere. In conduction, heat moves from areas of more heat to areas of less heat by direct contact. Warmer molecules vibrate rapidly and collide with other nearby molecules, transferring their energy.

Answer:

83.33ml

Explanation:

Firstly, let's notice that 200ml are equal to 0.2L

M=number of moles of the solute ÷ number of liters. Let's call the number of liter by x:

2.5=x÷0.2

x=2.5×0.2

x=0.5

It means you'll need 0.5 mol of HNO. But your solution have 6 moles per liter, so how much do you need? Divide the moles by 12 to have 0.5, so now you need to divide the liter per 12 too. The liter is equal to 1000ml, so:

1000ml÷12=83.33ml

Answer:

Activator effects a mixture if you put to much of the activator your using into a product or thing you are using.

Explanation:

For ex.

If you poor to much activator into slime it will make the slime hard and very wet it will ruin your slime completely so you will have to do it just right but start off pouring it slowly and mix and then more if it needs more.

Answer: No it does not

Explanation:

The law of conservation of mass states that mass is neither created nor destroyed and in this equation you start with 1 molecule of Cl and 1 of H, but on the reactants side you end up with 2 of each. To make it follow the law of conservation of mass you would have to balance the equation

Answer:

B: it has a high heat capacity

Explanation:

When any material has a high specific heat capacity/ heat capacity, it doesn't heat or cool very fast. So water can absorb more heat from the engine and can keep the engine cool or at low temperature for a longer period of time.

Answer:30.573 Billion atoms are in one gram

Explanation:

Answer:

c

Explanation:

troposphere is the answer

Explanation:

2/1×1.25

=2.5 mole of NaCl are produced

weight of NaCl produced = moles × molar mass of NaCl

weight of NaCl produced = 2.5×58.5

weight of NaCl produced =146.5 grams

Answer:

506.0 g sodium and 778.8 g chlorine gas

Explanation:

The elements from which sodium chloride (NaCl) is composed are sodium (Na) and chlorine (Cl). Thus, the chemical equation for the production of sodium chloride (NaCl) from sodium (Na) and chlorine gas (Cl₂) is the following:

2Na(s) + Cl₂(g) → 2NaCl(s)

According to the balanced equation, 2 moles of NaCl are produced from 2 moles of Na(s) and 1 mol of Cl₂. To produce 22.0 mol of NaCl, we need:

22.0 mol NaCl x 2 mol Na(s)/2 mol NaCl = 22.0 mol Na(s)

22.0 mol NaCl x 1 mol Cl₂/2 mol NaCl = 11.0 mol Cl₂

Now, we convert the moles of each reactant to grams with the molar mass (MM) of the compound:

MM(Na) = 23 g/mol

22.0 mol Na x 23 g/mol = 506.0 g Na(s)

MM(Cl₂) = 35.4 g/mol x 2 = 70.8 g/mol

11.0 mol Cl₂ x 70.8 g/mol = 778.8 g Cl₂

Therefore, it is required a mass of 506.0 grams of Na(s) and a mass of 778.8 grams of Cl₂ to produce 22.0 mol of NaCl.

Answer:

4Cr + __302 -->_2Cr203.....

Answer:

B

Explanation:

There's a three in front of the CH3COOH. But let's figure it out without that 3.

1 mol of CH3COOH has 3 H from CH3 and 1 hydrogen at the end. In all 4 hydrogens.

Now put the 3 in front 3CH3COOH multiplies everything by 3. So you had 4 before and with the 3 in front you must have 12.

Try it. Draw it out.

CH3COOH     has 4

CH3COOH     has 4

CH3COOH     has 4

Total                      12

That's B

Answer:

[tex]\Delta H=-92.7kJ[/tex]

Explanation:

Hello there!

In this case, according to the given information, we can infer that 890 kJ of energy are released when 1 mole of methane is burned; however, to find the total heat when 1.67 grams are burned, we first need to calculate the moles in this mass of methane:

[tex]1.67gCH_4*\frac{1molCH_4}{16.04gCH_4}=0.104molCH_4[/tex]

And thus, for calculating the resulting ∆H, we proceed as follows:

[tex]\Delta H=-890kJ/mol*0.104mol\\\\\Delta H=-92.7kJ[/tex]

Regards!

Answer:

2

H

2

+

O

2

=

2

H

2

O

Explanation:

From the original equation, you first need to write each component separately.

H

2

+

O

2

=

H

2

O

Left side: H = 2 ; O = 2 (number based on the subscript)

Right side: H = 2 ; O = 1 (number based on the subscripts; no subscript means that the element is just 1)

Notice that the number of H is already balance but the number of O is not. In order to balance the O, you need to multiply the element by 2, but you CANNOT do this by simply changing the subscript.

Hence,

H

2

+

O

2

=

2

H

2

O

Left side: H = 2 ; O = 2

Right side: H = 2 x 2 = 4 ; O = 1 x 2 = 2

Now, notice that the number of O is now balance (both are 2) but the number of H is not (since

H

2

O

is a substance and not an element, you need to multiply everything by 2). So, what to do?

You also multiply the left side H by 2. Hence,

2

H

2

+

O

2

=

2

H

2

O

Left side: H = 2 x 2 = 4 ; O = 2

Right side: H = 2 x 2 = 4 ; O = 1 x 2 = 2

The equation is now balanced.

Answer:

Meristematic Tissues. Tissues where cells are constantly dividing are called meristems or meristematic tissues. These regions produce new cells.

Explanation:

thank me later

Answer:

having a smooth or lubricated surface may help decrease friction.

Explanation:

Explanation:

hope it make sense to u :)

Answer:

Molar mass = [9(12.0)+8(1.01)+4(16.0)] = 180.1 g/mol Moles = 112 g 1 mol x 180.1 g = 0.622 mol (3 sig figs)

Explanation:

From the calculations and the principles of radioactivity, the age of the parent isotope is 144 years

The term radioactivity has to do with the spontaneous decay of a substance.

We know that we have about 25% parent isotope still remaining hence;

[tex]0.693/t1/2 =2.303/t log No/N\\When N =0.25 No and t1/2 = 72 years\\0.693/72 =2.303/t log No/0.25No\\0.0096 = 2.303/t *0.60206\\0.0096 = 1.3865/t\\t = 1.3865/0.0096\\t =144 years[/tex]

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Answer:

A. 144 years old

Explanation:

Answer:

true

Explanation:

Answer:

0.01 moles

Explanation:

14 g contains 1 mole

0.14g contains> (0.14*1)/14

= 0.01 moles

If the half-life for carbon-14 is 5730 years, then it will take 11,460 years to complete die of this sample.

Half life period is a time of decay in which concentration of reactant is left half of its initial concentration, means half of the reactant will convert into product.

Total time of decay will be calculated as:

T = (t)ⁿ, where

t = half life time = 5730 years

n = number of half lives = 2 (given)

On putting values, we get

T = (5730)² = 11,460 years

Hence required time for decay is 11,460 years.

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Answer:

The first part is 5 and the second part is 28,650

Answer:

A: Hydrogen bonding causes water to be strongly cohesive.

Explanation:

Water has a high surafce tension. Hence droplets of water

Water cannot dissolve non polar substances like oil; only polar

Water is actually less dense in solid form :)

Hydrogen bonding causes water to be strongly cohesive.

This sticking together of like substances is called cohesion. Depending on how attracted molecules of the same substance are to one another, the substance will be more or less cohesive. Hydrogen bonds cause water to be exceptionally attracted to each other. Therefore, water is very cohesive.

Cohesion, also called cohesive attraction or cohesive force, is the action or property of like molecules sticking together, being mutually attractive. It is an intrinsic property of a substance that is caused by the shape and structure of its molecules, which makes the distribution of surrounding electrons irregular when molecules get close to one another, creating an electrical attraction that can maintain a microscopic structure such as a water drop. In other words, cohesion allows for surface tension, creating a "solid-like" state upon which light-weight or low-density materials can be placed.

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Answer:

HOPE IT IS HELPFUL

Answer:

Cr is oxidised

and

Zn is reduced

[ Reduced reactant ] :

Cr^( + 3 ) + 3 e^( - 1 ) ===》 Cr^( 0 )

_____________________________

[ Oxidicided reactant ] :

Zn^(0) ===》Zn^( + 2 ) + 2 e^( - 1 )

Answer:

bismuth

Explanation:

i think if not i am so sorry

Answer:

8.73 × 10²⁴ formula units

Explanation:

To calculate the number of formula units a substance contain, we multiply the number of moles by Avagadro number (6.02 × 10²³)

number of formula units = 14.50 moles × 6.02 × 10²³

= 87.29 × 10²³

= 8.73 × 10²⁴ formula units.

Answer:

See Explanation

Explanation:

The way by which a metal is obtained from its ore is determined by the chemical reactivity of the metal.

Metals that are highly reactive are chiefly obtained by electrolysis of the metal salt. These metals are found high up in the metal activity series.

Metals that are at the middle of the series are moderately reactive and are obtained by electrolysis or by reduction since they still form ionic salts.

Metals that are far lower in the series can only be obtained by heating them in air because they are mostly unreactive.

Hence, moderately reactive metals at the middle of the series are not obtained by roasting in air.