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dezoksy [38]
2 years ago
13

An atom of a mystery element contains 7 protons, 7 neutrons, and 7 electrons.

Chemistry
1 answer:
posledela2 years ago
3 0

A-14

Explanation:

Mass number (MN) = Proton number + Neutron number

MN=7+7

MN=14

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In an electrically heated boiler, water is boiled at 140°C by a 90 cm long, 8 mm diameter horizontal heating element immersed in
RideAnS [48]

Explanation:

The given data is as follows.

Volume of water = 0.25 m^{3}

Density of water = 1000 kg/m^{3}

Therefore,  mass of water = Density × Volume

                       = 1000 kg/m^{3} \times 0.25 m^{3}

                       = 250 kg  

Initial Temperature of water (T_{1}) = 20^{o}C

Final temperature of water = 140^{o}C

Heat of vaporization of water (dH_{v}) at 140^{o}C  is 2133 kJ/kg

Specific heat capacity of water = 4.184 kJ/kg/K

As 25% of water got evaporated at its boiling point (140^{o}C) in 60 min.

Therefore, amount of water evaporated = 0.25 × 250 (kg) = 62.5 kg

Heat required to evaporate = Amount of water evapotaed × Heat of vaporization

                           = 62.5 (kg) × 2133 (kJ/kg)

                           = 133.3 \times 10^{3} kJ

All this heat was supplied in 60 min = 60(min)  × 60(sec/min) = 3600 sec

Therefore, heat supplied per unit time = Heat required/time = \frac{133.3 \times 10^{3}kJ}{3600 s} = 37 kJ/s or kW

The power rating of electric heating element is 37 kW.

Hence, heat required to raise the temperature from 20^{o}C to 140^{o}C of 250 kg of water = Mass of water × specific heat capacity × (140 - 20)

                      = 250 (kg) × 40184 (kJ/kg/K) × (140 - 20) (K)

                     = 125520 kJ  

Time required = Heat required / Power rating

                       = \frac{125520}{37}

                       = 3392 sec

Time required to raise the temperature from 20^{o}C to 140^{o}C of 0.25 m^{3} water is calculated as follows.

                    \frac{3392 sec}{60 sec/min}

                     = 56 min

Thus, we can conclude that the time required to raise the temperature is 56 min.

4 0
3 years ago
Due in a bit! please help tysm btw!
Free_Kalibri [48]

Answer:

Unbalanced

Explanation:

4 0
3 years ago
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Water molecules stick together by a force called?
patriot [66]

Answer:

Cohesion

Explanation:

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.

8 0
3 years ago
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PLZ HURRY I NEED THIS ANSWER LIKE... NOW
tresset_1 [31]

Answer:

Check for a change in total mass during the reaction. During the change to a chemical reaction, the mass of the products remain equal, which results in no change of the mass. The mass will change during nuclear reactions because of the large release of energy; that results in the difference of the accumulation. ^_^

6 0
3 years ago
What might you expect for the value of S∘ (entropy) for butane, C4H10?
Norma-Jean [14]

Answer:

340 J·K⁻¹mol⁻¹  

Explanation:

I looks like the standard entropy increases approximately linearly with the number of C atoms.

I plotted S° vs the number of C atoms and got the graph shown below.

It appears that S° for four carbon atoms should be about 340 J·K⁻¹mol⁻¹.·

4 0
2 years ago
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