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ad-work [718]
3 years ago
11

Which of these elements has the lowest melting point? (1) Li (3) K (2) Na (4) Rb

Chemistry
2 answers:
siniylev [52]3 years ago
4 0
The answer is (4) Rb. From observation, we can find that these four elements are from first column. The melting point from top to the bottom is from high to low. So the answer is (4).
natali 33 [55]3 years ago
4 0

Answer: Option (4) is the correct answer.

Explanation:

It is known that on moving down a group there will be decrease in melting point of the element because of increase in number of shells.

As a result, outermost electrons move away from the nucleus due to which there will be decrease in force of attraction between the protons and valence electrons. Hence, there will be decrease in melting point.

Therefore, the given elements are of same group and Rb has largest atomic size.

Thus, we can conclude that Rb has the lowest melting point.

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As an object falls freely near the earths surface , the loss in gravitational potential energy of the object is equal to its wha
Nitella [24]
Increase in kinetic energy as well as energy loss to the surroundings in the form of heat ( negligible)
4 0
2 years ago
Read 2 more answers
47.9 ml hrdrogen is collected at 26° Celsius and 718 torr. Find the volume occupied at STP
Temka [501]

Answer:

41.45 mL

Explanation:

Applying the general gas equation,

PV/T = P'V'/T'............... Equation 1

Where P = Initial pressure of hydrogen, V = Initial volume of hydrogen, T= Initial Temperature of hydrogen, P' = Final pressure of hydrogen, V' = Final Volume of Hydrogen, T' = Final Temperature.

make V' the subject of the equation

V' = PVT'/TP'................ Equation 2

Given: P = 718 torr = (718×133.322) N/m² = 95725.196 N/m², V = 47.9 mL = 0.0479 dm³, T = 26 °C = (26+273) = 299 K, T' = 273 K, P' = 101000 N/m²

Substitute these values into equation 2

V' = ( 95725.196×0.0479×273)/(299×101000)

V' = 0.04145 dm³

V' = 41.45 mL

4 0
3 years ago
Oxygen-Carbon Dioxide Exchange
leonid [27]

Answer:

Answer is below with the steps in order

Explanation:

4) Blood picks up carbon dioxide from the body

7) Heart pumps carbon dioxide rich blood to the lungs

8) Inhale

9) Nose traps germs in air

10) Air moves down the trachea

3) Air moves through bronchi into the bronchioles

6) Alveoli receive oxygen pass to blood

9) Oxygen passes into the blood

11) Alveoli receives carbon dioxide from the blood

12) Oxygen-rcih blood flows to the heart

3) Carbon Dioxide moves from bonchioles to bronchi

13)Carbon dioxide flows up

1) Heart pumps oxygen-rich blood to the body

The last <em>four of five</em> steps could be switched up a little bit since it all happens synchronously, but this is the most accurate interpretation.

8 0
2 years ago
The constant
Zigmanuir [339]

Answer:

75 kJ/mol

Explanation:

The reactions occur at a rate, which means that the concentration of the reagents decays at a time. The rate law is a function of the concentrations and of the rate constant (k) which depends on the temperature of the reaction.

The activation energy (Ea) is the minimum energy that the reagents must have so the reaction will happen. The rate constant is related to the activation energy by the Arrhenius equation:

ln(k) = ln(A) -Ea/RT

Where A is a constant of the reaction, which doesn't depend on the temperature, R is the gas constant (8.314 J/mol.K), and T is the temperature. So, for two different temperatures, if we make the difference between the two equations:

ln(k1) - ln(k2) = ln(A) - Ea/RT1 - ln(A) + Ea/RT2

ln (k1/k2) = (Ea/R)*(1/T2 - 1/T1)

k1 = 8.3x10⁸, T1 = 142.0°C = 415 K

k2 = 6.9x10⁶, T2 = 67.0°C = 340 K

ln(8.3x10⁸/6.9x10⁶) = (Ea/8.314)*(1/340 - 1/415)

4.8 = 6.39x10⁻⁵Ea

Ea = 75078 J/mol

Ea = 75 kJ/mol

4 0
2 years ago
What is the molecular formula of a compound if it’s empirical
snow_lady [41]
Depends on what compound we’re talking about here
4 0
3 years ago
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