Question

At 20°C, a length of copper wire has a resistance of 10.0 Ω What is its resistance when the wire is heated to 65°C? Let α = 0.004 at 20°C. Show all work and include units of measure. (2 points)

An object is placed 9.5 cm in front of a convex spherical mirror. Its image forms 3.2 cm behind the mirror. What is the radius of curvature of the mirror? Show all work. (2 points)


A candle is placed in front of a concave spherical mirror of focal length 9.60 cm. The image of the candle is inverted and 3.40 times as large as the candle itself. What is the distance of the candle to the mirror? Show all work and provide units of measure. (2 points)


An arrow pointing upward is placed to the left of a thin converging lens, as shown in the diagram. To identify the location of the image, a student draws three principal from the arrow. What feature should all three principal rays have in common? (2 points)



Dinosaur fossils are over 65 million years old. If some carbon from the dinosaur’s body remained in the fossil, would radiocarbon dating be useful for determining the age of the fossil? (1 point)
Yes, radiocarbon dating is useful for carbon-containing specimens of any age.
No, the carbon would have bonded chemically with other elements.
No, too much of the carbon-14 would have decayed for radiation to be detected.


A radioisotope has a half-life of 5.50 min and an initial decay rate of 7200 Bq. What will be the decay rate after 18.0 min? Show all work and include units of measure. (2 points)


A neutral atom of tin (Z = 50) has 69 neutrons. (a) How many protons does it have? (b) What is its mass number? (2 points)


Which type of nuclear reaction, fission or fusion, is used by nuclear power plants to produce electricity? Why? Be sure to include a brief explanation of the difference between fusion and fission. (2 points)


Radon-222 undergoes an alpha decay to become polonium-218. This reaction is an intermediate in a decay series that begins with uranium-238 and ends in lead-206.

A 1.0-gram sample of pure uranium-238 is sealed in a container at time = 0 years. To calculate the amount of radon-222 present in the container at any moment in the future, what is the minimum amount of information that must be known? (1 point)
The half-life of each decay reaction in the series from uranium-238 to lead-206
The half-life of each decay reaction in the series from uranium-238 to polonium-218
The half-life of each decay reaction in the series from uranium-238 to radon-222
The longest half-life in the series from uranium-238 to radon-222


The mass number of a neutral atom of iron (Z = 26) is 56. How many electrons does it have? (1 point)
56
30
26
13

Answer 1

Step-by-step explanation:

hope this helps you..............

Answer 2

Identify arrows pointing to bonding electrons.

✔ a, b, d

Identify arrows pointing to nonbonding electrons.

✔ c

Identify arrows pointing to structures containing sigma bonds.

✔ a, b, d

Identify arrows pointing to structures containing pi bonds.

✔ a

Step-by-step explanation:

On edg 2020