STAAR Science Grade 8 Sample Questions
Q.1 A substance that forms when two or more elements join chemically is
A) An ion
B) A compound
C) An atom
D) A formula
Answer is B. A compound. Explanation A compound is a substance that forms when two or more elements join chemically in a fixed proportion.
Q.2 What is the most common element in the human body ?
A) Carbon
B) Oxygen
C) Hydrogen
D) Calcium
Answer is B. Oxygen. Explanation The most abundant element in the human body is oxygen. It constitutes 65% of the total elements present in the body.
Q.3 What do elements in the same column of the periodic table have in common
A) similar chemical properties
B) same size
C) same atomic mass
D) same number of protons
Answer is A. similar chemical properties. Explanation Mendeleyev studied the elements properties and found that elements with similar properties ended up in the same column.
Q.4 What does the law of conservation of mass state ?
A) The total mass of the reactants is greater than the total mass of the products.
B) Mass can be created but not destroyed.
C)The total mass of the reactants is less than the total mass of the products.
D) The total mass of the reactants equals the total mass of the products.
Answer is D. Various scientists carried out the experiments like burning and rusting in air-tight containers so that gases could not escape or enter from outside the reaction. Then they measured the mass of reactants before the reaction and the product afterward. Hence they found that the total mass of the reactants equals the total mass of the products.
Q.5 How long does it take Earth to spin once on its axis ?
A) 12 hours
B) 24 hours
C) 36 hours
D) 20 hours
Answer is B. Explanation On the Earths axis, the Earth rotates. It takes 24 hours or one day to rotate once on its axis.
Q.6 Which list puts the stages of a butterflys life cycle in the correct order ?
A) egg, pupa, larva, adult
B) adult, egg, pupa, larva
C) egg, larva, pupa, adult
D) larva, egg, pupa, adult
Answer is C. Explanation The life cycle of a butterfly is made up of four stages. First stage is an egg, which a female adult lays. The second stage is called a larva. The larva of a butterfly is a caterpillar. The caterpillar eats and grows. The third stage is a pupa. In this stage the insect makes a hard case around itself. It changes form inside the case. When the insect comes out of the case, the insect is an adult. That is the fourth stage.
Q.7 What does Earth have that the moon does not have ?
A) An atmosphere
B) A rocky surface
C) Plains
D) Mountains
Answer is A. Explanation - The moon has no atmosphere. Astronauts who visit the moon must wear space suits that provide them with oxygen to breathe. With no atmosphere, the moon gets much hotter and much colder than Earth.
A) An area of high temperature
B) A high front
C) An area of high mountains
D) An area of high pressure
Answer is D. Explanation The letter H stands for high and indicates an area of high air pressure on a weather map. High-pressure areas usually bring fair weather.
Q.9 Which of these materials is a conductor or electricity ?
A) rubber
B) copper
C) plastic
D) glass
Answer is B. Copper. Explanation Copper is good conductor of electricity and rest all of them are bad conductor or electricity. Copper is a metal which let the electric charges to move through it and hence it is a good conductor of electricity.
Q.10 The change of a gas to a liquid is called
A) freezing
B) melting
C ) condensation
D) evaporation
Answer is C. Explanation When water vapor cools, it changes to liquid water. This change from a gas to a liquid is called condensation.
For more questions Study Guide and Preparation- State of Texas Assessments of Academic Readiness (STAAR)
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