PHYSICAL SCIENCE Q-3
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/59
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced | Call with Kai | Chat |
|---|
No analytics yet
Send a link to your students to track their progress
60 Terms
Which elements were mainly formed during Big Bang nucleosynthesis?
Hydrogen, Helium, and a little Lithium.
What evidence supports Big Bang nucleosynthesis?
Abundance of hydrogen and helium and Cosmic Microwave Background Radiation.
Where does stellar nucleosynthesis occur?
Inside stars.
Why does nuclear fusion stop at iron (Fe) in stars?
Forming iron does not release energy.
How are elements heavier than iron formed?
Through supernova explosions and neutron star collisions.
Who proposed that matter is made of tiny indivisible particles called atoms?
Democritus.
What idea of Aristotle dominated science for about 2,000 years?
Matter is made of four elements: Earth, Air, Fire, and Water.
What were the main contributions of alchemists?
Development of laboratory tools, distillation, filtration, and recording chemical reactions.
Who proposed that atoms combine to form compounds?
John Dalton.
Who discovered the electron?
J.J. Thomson.
What did Rutherford’s gold foil experiment reveal?
Atoms have a small, dense nucleus.
Who proposed electrons move in fixed energy levels?
Niels Bohr.
What is the basis of the modern periodic table?
Atomic number.
Which particle has a positive charge?
Proton.
Where are electrons located?
In energy levels around the nucleus.
What nuclear reaction joins small nuclei together?
Fusion.
What nuclear reaction splits a heavy nucleus?
Fission.
What is transmutation?
Converting one element into another.
How are synthetic elements produced?
By bombarding atoms with particles.
When is a molecule polar?
When electrons are shared unequally.
Which molecule is polar, H₂O or CO₂?
H₂O.
Which intermolecular force is present in all molecules?
London dispersion forces.
Which intermolecular force is the strongest?
Hydrogen bonding.
When does hydrogen bonding occur?
When hydrogen is bonded to nitrogen, oxygen, or fluorine.
What results from strong intermolecular forces?
Higher boiling point, higher surface tension, and slower evaporation.
Which material is malleable and a good conductor?
Metal.
Which material is used as a semiconductor?
Silicon.
Which macromolecule provides quick energy?
Carbohydrates.
Which macromolecule is used for long–term energy storage and insulation?
Lipids.
Which macromolecule stores genetic information?
Nucleic acids.
Why is structure important in macromolecules?
Structure determines function.
According to collision theory, when do reactions occur?
When particles collide with enough energy.
What factors increase reaction rate?
Higher temperature, higher concentration, smaller particle size, and catalysts.
What is the role of a catalyst?
Lowers activation energy and speeds up reactions without being used up.
What is the limiting reactant?
The reactant used up first.
What is theoretical yield?
The maximum possible amount of product.
How is percent yield calculated?
(Actual yield ÷ Theoretical yield) × 100.
What type of reaction releases energy?
Exothermic.
What type of reaction absorbs energy?
Endothermic.
What energy comes from falling water?
Hydroelectric energy.
What energy source comes from organic materials?
Biomass.
What converts sunlight directly into electricity?
Solar cells.
What is the main component of biogas?
Methane.
What chemical is commonly used as bleach?
Sodium hypochlorite.
Which cosmetic ingredient acts as a moisturizer?
Glycerin.
What is the function of emulsifiers?
To mix oil and water.
Why should cleaning chemicals not be mixed?
They may react dangerously and release toxic fumes.
Why are safety labels important?
Chemicals can irritate skin, cause burns, or release toxic gases.
Why must safety labels like “use in well–ventilated area” be followed? be followed?
(Chemicals may release harmful or toxic fumes..)