مراجعه علوم تاسع الفصل الاول

What defines a gas? 

• Gases have a definite volume​and shape.

• Gases have a definite volume​but take the shape of their container.​

• Gases have no definite volume or​shape.​

• Gases have a definite shape ​but no definite volume. ​

When one substances turns into another, what kind of change has taken place? 

• chemical reaction ​

• physical reaction

• extensive reaction​

• nuclear reaction ​

The law of conservation of mass states that:  ​

• Matter can be created and destroyed. ​

• Matter can be created but not destroyed.​

• The products of a reaction always ​have a greater mass than the ​reactants.​

• The products of a reaction must ​have the same mass as the ​reactants.​

Which is NOT a technique for separating a homogenous mixture?

• crystallization ​

• distillation

• filtration

• . chromatography 

Which of the following is a heterogeneous mixture? ​

• seawater

• silver mercury amalgam​

• atmosphere​

• salad dressing ​

What is a period on the periodic table of the elements?  ​

• a vertical columns ​

• even numbered elements only ​

• horizontal rows

• the last vertical column only ​

An element is a substance that cannot be

• divided into simpler substances. ​

• combined to form a mixture. 

• combined to form an element

• different phases

Which of the following is NOT a physical property of water? 

• Ice melts at 0°C

• Water boils at 100.​

• Water reacts violently with ​pure sodium. ​

• Water is a liquid at room ​temperature.​

28.0 grams of nitrogen gas reacts completely with 6.0 grams of hydrogen to form 34.0 grams of ammonia. What does this demonstrate? 

• the law of conservation of energy

• sublimation ​

• distillation ​

• the law of conservation of mass​

What is the best way to separate salt dissolved in water?

• sublimation ​

• crystallization ​

• freezing

• filtration