Latest Physical Science Reviewer 10

1. Which of the following is an organic compound?

A. Baking soda

B. Glucose

C. Limestone

D. Sulfuric acid

Ans: B. Glucose

-Just because something contains carbon, it doesn’t mean it’s organic. Organic compounds don’t usually have Na⁺ and HCO₃ which makes up baking soda (NaHCO₃). Limestone or calcium carbonate (CaCO₃) is in organic. Sulfuric acid does not certain nay carbon atom. Glucose contains 6 carbon atoms, 12 hydrogen atoms and six oxygen atoms, which makes it and any other carbohydrate an organic compound.

2. Which of the following serves as thermal insular in the body?

A. Carbohydrates

B. Fats

C. Nucleic acids

D. Proteins

Ans: B. Fats

-Fats conduct heat very slow so having a layer under the skin keeps metabolic het in the body.

3. In DNA, which is the correct complementary pairing of the nitrogenous bases?

A. AG and CT

B. AA and GG

C. AC and GC

D. AT and GC

Ans: D. AT and GC

-The rule of nucleotide pairing is the purine adenine (A) always pairs with the pyrimidine thymine (T) and the pyrimidine cytosine (C) always pairs with the purine guanine (G).Only with A and T and C and G are the opportunities to establish hydrogen bonds. These relationship are often called the rules of Watson-Crick base pairing, named after the two discovered their structural basis.

4. Which biomolecule is considered the building blocks of tissues and organs?

A. Carbohydrates

B. Lipid

C. Nucleic acid

D. Protein

Ans: D. Protein

-Protein play a vital role in the cellular maintenance, growth and functioning of the human body. Serving as the basic structural molecules of all tissues in the body, Protein makes up approximately 17% of the total body weight. Proteins are essential; component for every type of tissues. The amount of protein needed to build new tissue or maintain structure and function depends on the rate of renewal on the stage of growth and development.

5. What is the main function of the hormone oxytocin in the body?

A. Controls water secretion by the kidneys

B. Stimulates conversion of glycogen to glucose

C. Controls blood – glucose level and storage of glycogen

D. Stimulates contraction of the uterine muscles and secretion of milk by the mammary glands

Ans: D. Stimulates contraction of the uterine muscles and secretion of milk by the mammary glands

-Hormones are chemical substances that act as control agents in the body, often regulating metabolic pathways. Oxytocin stimulates contraction of the uterine muscles and secretion of milk by the mammary gland. Glucagon stimulates conversion of glycogen to glucose. Insulin controls blood-glucose level and storage of glycogen. Vasopressin controls water secretion by the kidneys.

6. The half-life of thorium-234 is 24 days. How much 5g of ^234th would be left after 48 days?

A. 0.625 g

B. 1.25 g

C. 2.50 g

D. 3.75 g

Ans: B. 1.25 g

-half-life of Thorium- 234 after 24 days= 5/2 = 2.5g

 half-life of Thorium- 234 after 48 days= 2.5/2 = 1.25g

7. What happens when there is a loss of an alpha particle from the nucleus?

A. No change in the mass number or atomic number

B. Loss of 4 in the mass number,  loss of 2 in the atomic number

C. Loss of 2 in the mass number, loss of 4 in the atomic number

D. No change in the mass number, increase of 1 in the atomic number

Ans: B. Loss of 4 in the mass number,  loss of 2 in the atomic number

-During alpha emission, the nucleus is initially in an unstable energy state. An internal change takes place in an unstable nucleus and an alpha particle is ejected leaving a decay product. The atom has then two protons along with two neutrons.

8. What is the balanced equation of ⁷⁰₃₁Ga that undergoes beta decay?

A. ⁷⁰₃₁Ga  ---------------> ⁷⁰₃₁X + ⁰₀β

B. ⁷⁰₃₁Ga  --------------->⁷⁰₃₂X + ⁰_-1β

C. ⁷⁰₃₁Ga  --------------->⁷⁰₃₁X + ⁰_-1β

D. ⁷⁰₃₁Ga  ---------------> ⁷¹₃₁X + ^-1₀β

Ans: C. ⁷⁰₃₁Ga ------------->  ⁷⁰₃₁X + ⁰_-1β

-Write the skeleton equation including the mass number, atomic number, and symbols of all the particles, using X for the unknown nuclide.

Mass number: 70=70+0                           Atomic number: 31=32-1

                               ⁷⁰_{31Ga ---------->}  ⁷⁰₃₁X + ⁰_-1 β

9. What is the medical application of the isotope P-32 with a half-life of 4.3 days?

A. Liver imaging

B. Gastrointestinal diagnosis

C. Treatment of leukemia

D. Treatment of hyperthyroidism

Ans: C. Treatment of leukemia

-Some radioisotopes are used in the treatment of cancer because they have the ability to kill living tissues. Isotope P-32 is used for treatment of leukemia. Isotopes Ce-14 is used for gastrointestinal diagnosis. Isotope Au-198 is used for liver imaging. I-131 is used for treatment of hyperthyroidism.

10. Which of the following poses a serious obstacle to the development of commercial fusion power plants?

A. Scarcity of deuterium

B. Public concern about safety

C. Dwindling supply of uranium

D. Exceedingly high activation energy

Ans: D. Exceedingly high activation energy

- Activation energies for fusion reactions are generally high because the protons in each nucleus will tend to strongly repel one another, as they each have the same positive charge, thus it will be very difficult to contain.

11. A radioisotope is considered a tracer when it used to ___________.

A. kill cancerous tissues

B. Kill bacteria in food

C. Determine the age of artifacts

D. Determine the way plants absorb fertilizers

Ans: D. Determine the way plants absorb fertilizers

-A radioisotope used to follow the path of a chemical process is known as tracer. The fact that it can be detected or traced as it decays makes it possible to determine its location at all times. It used to measure the speed of chemical process and track the movement of a substance through a natural system just like in the case of plants absorbing fertilizer.

12. Identify the following quantities as scalar or vector respectively: mass of an object, the number of leaves on a tree, and wind velocity.

A. Scalar, Scalar, Vector

B. Scalar, Vector, Scalar

C. Vector, Scalar, Scalar

D. Vector, Scalar, Vector

Ans: A. Scalar, Scalar, Vector

-A scalar is a quantity that is described completely by specifying its magnitude only. A vector is a quantity that can be described completely if both its magnitude and direction are given. Mass and number of leaves are both scalar while wind velocity is vector.

13. Which of the following is a scalar quantity?

A. Acceleration

B. Temperature

C. Velocity

D. Weight

Ans: B. Temperature

-Acceleration, velocity and weight indicate both magnitude and direction, hence they are all vectors. Temperature indicates magnitude only so it is a scalar.

14. Which of the following describes a vector quantity?

A. It specifies direction only.

B. It specifies magnitude only.

C. It can be a dimensionless a vector quantity.

D. It specifies both magnitude and direction.

Ans: D. It specifies both magnitude and direction.

-See number 112 for the explanation

15. A man pushes against the wall with 25 pounds of force. The wall does not move. What is the resultant force?

A. -25 pounds

B. 0 pounds

C. 50 pounds

D. 75 pounds

Ans: B. 0 pounds

-Since the forces cancel each other out.

16. In a coordinate system, a vector is oriented at angle with respect to the x axis. They components of the vector equals the vector’s magnitude multiplied by which trigonometric function?

A. Cos angle

B. Cot angle

C. Sin angle

D. Tan angle

Ans: C. Sin angle

-If a vector is oriented at an angle with respect to the axis, using right triangle trigonometry, Fx is adjacent to angle A, Fy is positive to angle A and F is the hypotenuse. The cosine function is associated with the x component and the sine function is associated with the y componenet.

17. An ant on a picnic table travels 30 cm due east, then 25 cm northward and finally 15 cm due west. What is the magnitude of the ant’s displacement relative to its point of origin?

A. 29 cm

B. 58 cm

C. 70 cm

D. 99 cm

Ans: A. 29 cm

-Since the displacement of the ant forms a right triangle, use the Phytagorean Theorem:

18. What will happen to a moving object in the sum of all the forces acting on it is zero?

A. It will accelerate uniformly.

B. It will slow down and stop.

C. It will change the direction of its motion.

D. It will continue moving with constant velocity.

Ans: D. It will continue moving with constant velocity.

-For something to change direction or accelerate, there must be an unbalanced force acting on it. Newton’s First states that an object in motion will stay in motion at constant velocity unless acted upon by an unbalanced force.

19. Acceleration is always in the direction of the _________.

A. displacement

B. final velocity

C. initial velocity

D. net force

Ans:  D. net force

-Newton’s Second Law of Motion state that the acceleration of object as produced by a net forced is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

20. A brick slides on the horizontal surface. Which of the following will increase the magnitude of the frictional force on it?

A. Putting a second brick on top

B. Decreasing the mass of the brick

C. Increasing the surface area of contact

D. Decreasing the surface area of contact

Ans: Putting a second brick on top increase the mass thereby increasing the normal force, hence the total frictional force increases. Frictional force is independent of the area of contact.

To download this reviewer, just click here. Good luck and God bless!