When an object burns, the quantity of the ashes that remain is smaller than the original object that was burned. What happened to the rest of the object?

Approved eye protection devices (such as goggles) are worn in the laboratory

You are heating a substance in a test tube. Always point the open end of the tube 

When working in the laboratory chemicals, one must know all the safety symbols. Toxic or poisonous material symbol indicates the presence of substances that is harmful to an individual if they enter the body. Possible exposure to toxic material is through inhalation, skin contact, and ingestion. Which of the following safety precautions symbol represents it?

Most of the materials in the laboratory must be handle with care. There are hazardous or corrosive substances in the lab that can eat away the skin if you come into direct contact with them. Instructors who handle corrosive substances should be properly trained and wear gloves, protective clothing, and face protection. Which of the following safety precautions symbol represents Corrosive Hazard Laboratory safety?

(A) The letters are the choices itself. On a cold morning, your car does not start.  You say, “Oh no! The battery is dead!”. (B)Your friend who works on cars uses a battery tester and finds that the battery has a full charge. (C) Your friend says’ “Maybe corrosion is causing a bad connection in the electrical circuit, preventing the car from starting.” (D) Your friend cleans the terminals and the car starts. Which statement from the above paragraph  

     is an observation?

(A) The letters are the choices itself. On a cold morning, your car does not start.  You say, “Oh no! The battery is dead!”. (B)Your friend who works on cars uses a battery tester and finds that the battery has a full charge. (C) Your friend says’ “Maybe corrosion is causing a bad connection in the electrical circuit, preventing the car from starting.” (D) Your friend cleans the terminals and the car starts. Which statement from the above paragraph  

     is a hypothesis?

(A) The letters are the choices itself. On a cold morning, your car does not start.  You say, “Oh no! The battery is dead!”. (B)Your friend who works on cars uses a battery tester and finds that the battery has a full charge. (C) Your friend says’ “Maybe corrosion is causing a bad connection in the electrical circuit, preventing the car from starting.” (D) Your friend cleans the terminals and the car starts. Which statement from the above paragraph  

     describes the experiment is done?

(Answer as many as needed)

Using the table above, what must be tested during the experiment?

Considering that the yeast produces CO₂, which of the following components produce a  large amount of CO₂?

Significant figures are the number of digits in a measurement, that contribute to the degree of accuracy of the value.

Which of these measurements have four significant figures?

      I. 4.098g                             III. 0.0498g    

II. 3.0 X 10³                        IV. 40.50g

The correct representation of 56098 g using

       scientific notation is _______.

Based on figure 1, Density is a measure of mass per unit of volume. Which of these samples have the same density (use the formula D=g/mL, when mL= cm³)?           

What is the volume of the

     liquid in this graduated

     cylinder?

Which substance has a density of 11.4 g/cm³?

Which substance has the greatest density?

Which substance has the least density? 

The two beakers shown below contain pure water (density = 1 g/mL). Which of these properties is the same for the water in both beakers?

At 20℃, the density of air is 1.20 g/L. It is  composed of 78% nitrogen, 28% oxygen and 0.4% carbon dioxide. Nitrogen’s density is 1.17 g/L. Oxygen’s density is 1.33 g/L and carbon dioxide’s density is 1.98 g/L.

What will happen to a balloon filled with oxygen and nitrogen?

At 20℃, the density of air is 1.20 g/L. It is  composed of 78% nitrogen, 28% oxygen and 0.4% carbon dioxide. Nitrogen’s density is 1.17 g/L. Oxygen’s density is 1.33 g/L and carbon dioxide’s density is 1.98 g/L.

Air is mainly a mixture of nitrogen, oxygen and some gases. Which gas is the main component and least density?

A piece of copper metal is heated in a flame.  The surface of the metal becomes black, but the metal does not melt or change in any other way.  The black color must be due to a …

Hot coffee is poured into a cold stream.  Which of the following statements is correct?

An exothermic is a process that allow substance to released heat. Which one of the following is an exothermic process?

The electron is a subatomic particle, symbol e⁻ or β⁻, whose electric charge is negative one elementary charge. The region where electrons can be found is the called  

Early 1700s the continuous quest of particles as small as atom had begun. The first to formally use the name atom was       

Thompson’s model of the atom was known as:

The planetary model of the atom was stated by:

Rutherford conducted his famous "Gold Foil" experiment to learn about atomic structure. The results of his experiment are illustrated in the image. What does the experiment tell you about the structure of an atom?

How many protons does the atom have?

How many protons does the Y atom have?

What is the atomic number of the atom?

What is the mass number of the atom?

Describe the location of non-metals on the periodic table.

What is the number of nuetron of element X?

What is the mass number of element Y?

The air you breathe is composed of about 20% oxygen and 80% nitrogen. Which atomic window best represents a sample of air?

An atom composed of 32 protons, 32 electrons and 41 neutrons is

Which of these statements about periodic table are correct?

      I. Elements are arranged in order of increasing atomic number.

      II. A period is a horizontal row.

      III. A group is a vertical column.

The major portion of an atom’s mass consists of

Mark is observing a burning candle. He notices the melted wax drips down the side of the candle and hardens again. Which of the following tells what the candle has undergone?

         Cr_(s) + Fe(NO₃)_2(aq)        →      Fe_(s) + Cr(NO₃)_3(aq)

From the chemical reaction above, what is/are the reactant/s in the reduction and oxidation reaction?

  Cr_(s) + Fe(NO₃)_2(aq)      →        Fe_(s) + Cr(NO₃)_3(aq)

From the chemical reaction above, . Identify the products in the reaction.

How many electrons does

        Silicon contains?

Electrons involved in bonding between atoms that are found in the outermost shells are called

Photosynthesis is the process by which green plants manufacture their own food. This occurs in presence of sunlight and other raw materials, namely carbon dioxide and water and later on produces sugar and oxygen. The illustration above shows an example of ________________.

In photosynthesis process, the presence of sunlight, carbon dioxide and water are called  _________ of the reaction.

Chemical reaction is a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Which of the following is NOT a way to tell if a chemical reaction has taken place?

Based on the chemical reaction above, mass is conserved. This means that ___________

In the chemical reaction CH₄ + 2O₂ → CO₂ + 2H₂O, there are reactants on the left of the equation and products on the right. The total mass of the reactant of 16 g methane and 28 g oxygen is equal to ________.

The graph shows that the rate of reaction and temperature are _______ related and that the rate ________ as the temperature increases.

Which of the following is the full electron configuration for a neutral atom of manganese?

What is the atomic mass of Manganese?

Which is the electron configuration of atomic number 18?

Involve the reaction between diatomic element P and diatomic element Q to form compound P₃Q. Which part of the chemical reaction is P₃Q?

Involve the reaction between diatomic element P and diatomic element Q to form compound P₃Q. In The reaction in the left, the arrow sign symbolizes ____________.

A mixture of water with boiling point of 100°C and ethyl alcohol of 78°C is separated through distillation. Which substance will be collected first in 8?

The figure above shows a distillation set up. What do you call the part where water is stored and cools the vapor causing it to liquify (number 5)?

In an electromagnetic wave, an electric field exists perpendicular to a magnetic field, and both fields are perpendicular to the direction of travel of the wave. These characteristics indicate that an electromagnetic wave is which of the following wave types?

The figure below shows regions of the electro-magnetic spectrum. Which of the following devices is designed to produce electromagnetic radiation with the longest wavelength in order to operate?