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juin [17]
3 years ago
10

The atomic number of yttrium is 39. The atomic mass of one of its isotopes is 89. How many neutrons are in an atom of this isoto

pe?
Physics
1 answer:
gogolik [260]3 years ago
8 0
50. The atomic mass is essentially a tally of all of the atoms in the nucleus, since electrons are essentially negligible in mass.
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For a particular reaction, the change in enthalpy is 51kJmole and the activation energy is 109kJmole. Which of the following cou
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Answer

given,

change in enthalpy = 51 kJ/mole

change in activation energy = 109 kJ/mole

when a reaction is catalysed change in enthalpy between the product and the reactant does not change it remain constant.

where as activation energy of the product and the reactant decreases.

example:

ΔH = 51 kJ/mole

E_a= 83 kJ/mole

here activation energy decrease whereas change in enthalpy remains same.

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Small-plane pilots regularly compete in "message drop" competitions, dropping heavy weights (for which air resistance can be ign
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plane is flying at an altitude of 70 m

now if an object is dropped from it then time taken by object to drop on ground will be given as

y = v_i* t + \frac{1}{2}at^2

here initial speed in vertical direction must be zero as plane is moving horizontal

given that

y = 70 m

a = 9.8 m/s^2

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t = 3.77 s

now since the plane is moving horizontally with speed v = 44 m/s

so the horizontal distance moved by the object will be

d = v_x * t

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3 years ago
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Your code returns a number of 99.123456789 +0.00455679 for your calculation. How should you report it in your lab write-up?
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Answer: Your code returns a number of 99.123456789 +0.00455679

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But you must round your results. In the number you can see that after the 3 comes a 4, so the 3 stays as it is.

in the error, after the 4 comes a 5, so it rounds up.

So the final presentation will be 99.123 +- 0.005

you are discarding all the other decimals because the error "domains" them.

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3 years ago
What is the ostrich's average acceleration from 9.0 to 18 seconds?
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The average acceleration from 9 to 18 seconds is 6 meters per second.

The graph shows that from 9 to 18 seconds the speed of the ostrich stays at a steady 6 meters per second.

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3 years ago
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