QuestionQuestion

[1] If the distance between two stars is doubled, the force of gravity between them __
A ) is unchanged
B ) increases by a factor of four
C ) decreases by a factor of four
D ) decreases by a factor of two

[2] Which of these statements is false about activation energy?
A ) It determines the rate of a chemical reaction
B ) It is the energy barrier of a chemical reaction
C ) Catalysts lower the activation energy of a reaction
D ) It is lower for endothermic reactions than for exothermic reactions

[3] Which of these is a vector quantity?
A ) mass
B ) energy
C ) power
D ) momentum

[4] If we push an object at constant velocity, how does the friction acting on the object compare to our pushing force
A ) equal to the pushing force
B ) greater than the pushing force
C ) less than the pushing force
D ) none of the above

[5] Which of these are true of gamma rays:
I) Its frequency is lower than ultraviolet radiation. II) Gamma irradiation can be used to destroy harmful micro-organisms. III) They are electromagnetic waves. IV) They can bring about genetic mutations in humans.
A ) I only
B ) II only
C ) II, III and IV
D ) none of the above

[6] When alpha particles pick up electrons, they become _________
A ) Helium gas
B ) Hydrogen gas
C ) Lithium
D ) none of the above
[7] The force responsible for chemical bonding is
A ) nuclear
B ) gravitational
C ) electromagnetic
D ) none of these

[8] If atoms unite by transfer of electrons, they form
A ) an element
B ) an ionic compound
C ) a polar molecule
D ) a covalent compound

[9] Substances that are diminished in a chemical reaction are called
A ) products
B ) reactants
C ) catalysts
D ) solvents

[10] Water has a high specific heat capacity. This property explains the fact that _____
A ) water has a high humidity,
B ) water can boil quickly
C ) water has a moderating effect on climate
D ) water has a linear shape

[11] In metals, heat transfer occurs through
A ) convection
B ) conduction
C ) none of the above
D ) all of the above

[12] The source of all magnetism is
A ) tiny bits of iron
B ) small lodestones
C ) the motion of electrons
D ) none of the above

[13] A metal cube of mass 3kg is immersed halfway in water. If the volume of water displaced is 3L, what is the density of the metal?
A ) 1000kg/m3
B ) 500kg/m3
C ) 600kg/m3
D ) 800kg/m3

[14] The period of a wave is
A ) the distance between identical parts of the wave
B ) the number of complete oscillations in a given time period
C ) the speed of the wave
D ) the time it takes for a complete oscillation

[15] Which of these is an electromagnetic wave?
A ) sound waves
B ) water waves
C ) seismic waves
D ) light waves

[16] The speed of sound
A ) increases with temperature
B ) decreases with temperature
C ) is unaffected by temperature
D ) none of the above

[17] The bending of light when it travels from one medium into another is known as____
A ) refraction
B ) reflection
C ) absorption
D ) none of the above

Section-2
Answer all questions in this section. Show your work and explain your reasoning in detail.

[18] An isotope of the element Thallium, Tl-206, undergoes beta decay with a half life of 3.1 minutes. Assume you begin with 1.0 grams of the thallium isotope, what mass of the isotope will be left after 9.3 minutes have elapsed?

[19] A solution has a hydronium-ion concentration of 1.0 x 10-5 mol per liter. What is the pH of this solution? Is this solution acidic or basic? What is the hydroxide-ion concentration of this solution?

[20] Balance the following chemical equations.
a. Fe+ O2  Fe2O3
b. F2 + HBr  Br2 + HF

Section: Section-3
Answer all questions in this section. Explain in detail.

[21] How would you explain the difference between kinetic energy and potential energy? Give an example from the real world where potential energy is transferred to kinetic energy.


[22] Describe the difference between an exothermic reaction and an endothermic reaction. In an endothermic reaction, is the energy of the reactants higher or lower than that of the products? Draw an energy diagram for an endothermic reaction and label the axes.

[23] What is a circuit? Identify 3 differences between a series and a parallel circuit. How are the devices in a typical home connected – in series or in parallel? How do you know?

[24] How would you describe radioactive decay? Give a real-world application of this concept. Name two types of radiation emitted by radioisotopes and identify a difference between these two types of radiation

[25] What is Newton’s law of universal gravitation? Is there any gravity on the moon? What is the gravitational force on the moon dependent on? Planets A and B have identical masses but the distance between planet A and the earth is three times the distance between planet B and the earth. How does the weight of an object on A compare to the weight of the object on B?

[26] Describe the difference between any two methods of heat transfer. Why do we feel hot when we wear black on a sunny day? If we wanted to keep warm on a cooler day, should you wear black or light-colored clothing? Why?

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These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice. Unethical use is strictly forbidden.

1. If the distance between two stars is doubled, the force of gravity between them:
( C ) decreases by a factor of four

2. Which of these statements is false about activation energy?
( A ) It determines the rate of a chemical reaction

3. Which of these is a vector quantity?
( D ) Momentum

4. If we push an object at constant velocity, how does the friction acting on the object compare to our pushing force
( A ) equal to the pushing force...

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