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2 years ago

The lanthanides are all radioactive true or false

Physics

1 answer:

Oksi-84 [34.3K]2 years ago

3 0

Answer:

False

Explanation:

All the lanthanides are not radioactive in nature. Just one of the lanthanides are radioactive.

The lanthanides belong to the f-block on the periodic table
Only Promethium in this group are radioactive in nature.
Other elements in the lanthanide series might have radioactive isotopes.

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Calculate the total resistance in a parallel circuit made up of resistances of 2, 3, and 4.

Tamiku [17]

Answer:

0.91

Explanation:

as equivalence resistance can be found out using the

1/Req = 1/r1 +1/r2 +1/r3......

now, 1/req= 1/2+1/3+1/4

=6/12+4/12+3/12

=13/12

i.e, req =12/13 =0.91

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3 years ago

The orbital radius of the Earth (from Earth to Sun) is 1.496 x 10^11 m.

mrs_skeptik [129]

Explanation:

The orbital radius of the Earth is $r_1=1.496\times 10^{11}\ m$

The orbital radius of the Mercury is $r_2=5.79 \times 10^{10}\ m$

The orbital radius of the Pluto is $r_3=5.91 \times 10^{12}\ m$

We need to find the time required for light to travel from the Sun to each of the three planets.

(a) For Sun -Earth,

Kepler's third law :

$T_1^2=\dfrac{4\pi ^2}{GM}r_1^3$

M is mass of sun, $M=1.989\times 10^{30}\ kg$

So,

$T_1^2=\dfrac{4\pi ^2}{6.67\times 10^{-11}\times 1.989\times 10^{30}}\times 1.496\times 10^{11}\\\\T_1=\sqrt{\dfrac{4\pi^{2}}{6.67\times10^{-11}\times1.989\times10^{30}}\times1.496\times10^{11}}\\\\T_1=2\times 10^{-4}\ s$

(b) For Sun -Mercury,

$T_2^2=\dfrac{4\pi ^2}{6.67\times 10^{-11}\times 1.989\times 10^{30}}\times 5.79 \times 10^{10}\ m\\\\T_2=\sqrt{\dfrac{4\pi^{2}}{6.67\times10^{-11}\times1.989\times10^{30}}\times 5.79 \times 10^{10}}\ m\\\\T_2=1.31\times 10^{-4}\ s$

$T_3^2=\dfrac{4\pi ^2}{6.67\times 10^{-11}\times 1.989\times 10^{30}}\times 5.91 \times 10^{12}\\\\T_3=\sqrt{\dfrac{4\pi^{2}}{6.67\times10^{-11}\times1.989\times10^{30}}\times 5.91 \times 10^{12}}\\\\T_3=1.32\times 10^{-3}\ s$

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3 years ago

PLZ help 10 points!!! space question!

irga5000 [103]

Answer:

B. They are smaller and made of rocky material

Explanation:

i think it's right??

5 0

2 years ago

Please help! I have another part to this too.

JulsSmile [24]

first one is true, there's no net force acting on it thats greater than another or making it unbalanced, if there was the object would be in some kind of motion

All scientist use meters, that way scientist can share information across country without needing to convert the data.

3. is air resistance

4. The large rock

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2 years ago

6. A 2000 kg spacecraft is located 9.2x10 m from the center of the earth. The mass of the earth

Zina [86]

The answer is -i, trust me.

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2 years ago