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3 years ago

What is true about the element Francium (Fr, atomic number 87)? choose 3

Chemistry

1 answer:

larisa86 [58]3 years ago

6 0

Answer :

(B) It is likely to form ionic bonds

(D) It is in period seven

(E) It is a metal

Explanation :

Francium is an element whose symbol is 'Fr' and atomic number is 87.

Group 1 alkali metals consists elements Lithium, Sodium, Potassium, Rubidium, Caesium and Francium. Periodic table also shown below.

Francium belongs to the group 1 (alkali metal) and it is in period seven.

It has one valence electron, the electronic configuration of Francium is [Rn} $7s^{1}$ .

Alkali metals have tendency to form ionic compounds because they have +1 charge.

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Radar detectors use radio waves to measure the speed of moving

bagirrra123 [75]

Answer:

1.7x10^8 Hz

Explanation:

Frequency could be explained as the number of occurrences of a repeating event at a time

Given:

wavelength = 1.8 meters

The frequency f of the waves can be calculated using f = c / λ

Where c (m/s) is the speed of the wave

λ (m) is the wavelength

Speed c= 3*10^8 m/s

Frequency f= 3*10^8 /1.8

Frequency= 1.7x10^8 Hz

Therefore,the frequency of waves from a radar detector is 1.7x10^8 Hz

6 0

3 years ago

Why k has more shielding effect than Na?

lara [203]

Explanation:

As the charge of all electrons are equal, the repulsive force exerted by each of them is also going to be equal. So, as K has more electrons repulsing its valence electron than Na, it has greater electron shielding.

8 0

3 years ago

Which out of two has stronger forces of attraction sugar or water very sort answer

Marina CMI [18]

Sugar. It is solid and its atoms have less kinetic energy to overcome the bonding force. So, the bonding force is stronger than water, which is liquid and has more kinetic energy to overcome the bonding force of atoms. So, water has less strong force of attraction. Hence, sugar has stronger forces of attraction.

8 0

3 years ago

Free-energy change, ΔG∘, is related to cell potential, E∘, by the equationΔG∘=−nFE∘where n is the number of moles of electrons t

mart [117]

Answer:

a) $\Delta G=372490 J$

b) $\Delta G=-568614 J$

Explanation:

a) The reaction:

$Mg(s) +Fe^{2+}(aq) \longrightarrow Mg^{2+}(aq) + Fe(s)$

The free-energy expression:

$\Delta G=-n*F*E$

$E=E_{red}-E_{ox]$

The element wich is reduced is the Fe and the one that oxidates is the Mg:

$-0.44V=E_{red}-(-2.37V)=1.93V$

The electrons transfered (n) in this reaction are 2, so:

$\Delta G=-2mol*96500 C/mol * 1.93 V$

$\Delta G=-372490 J$

b) If you have values of enthalpy and enthropy you can calculate the free-energy by:

$\Delta G=\Delta H - T* \Delta S$

with T in Kelvin

$\Delta G=-675 kJ*\frac{1000J}{kJ} - 298K*-357 J/K$

$\Delta G=-568614 J$

7 0

3 years ago

HgS + O2 → HgO + SO2

Igoryamba

Answer:

2HgS + 3O2 → 2HgO + 2SO2

The coefficients are: 2, 3, 2, 2

Explanation:

HgS + O2 → HgO + SO2

The equation can be balance as follow:

Put 3 in front of O2 as shown below:

HgS + 3O2 → HgO + SO2

Now we can see that there are 6 atoms of O on the left side of the equation and a total of 3 atoms on the right side. It can be balance by putting 2 in front of HgO and SO2 as shown below:

HgS + 3O2 → 2HgO + 2SO2

Now we have 2 atoms of both Hg and S on the right side and 1atom each on the left. It can be balance by putting 2 in front of HgS as shown below:

2HgS + 3O2 → 2HgO + 2SO2

Now the equation is balanced.

The coefficients are: 2, 3, 2, 2

The law of conservation of mass(matter) states that matter(mass) can neither be created nor destroyed during a chemical reaction but changes from one form to another. An unbalanced equation suggests that matter has been created or destroyed. While a balanced equation proofs that matter can never be created but changes to different form. This is the more reason we have count the atoms of an element on both side of the equation to see if they are balanced irrespective of the new form they assume in the product

5 0

3 years ago