Answer:
<em><u>A. Neither the subjects nor the researchers can bias the results.</u></em>
Explanation:
As described, a double- blind study is one in which the researcher and his study does not know the person receiving the actual treatment.
Researchers can be bias in their studies as they seek to establish and fine tune results in the way the best favors them. A double-blind study helps to bridge this gap to prevent bias that might be introduced into an experimental set up or while interpreting results.
1. The answer is; B
This is because the soup has a higher temperature than the surrounding air. The heat will move from hotter object to the cooler object in search of thermal equilibrium. Heat transfer will only stop when the soup and the surrounding air have more or less the same temperatures.
2. The answer is; B
No mas is required because radiation (which are mainly electromagnetic waves) can transfer energy even through a vacuum. Other forms of energy transfer (such as convection and conduction)involve the transfer of vibrational motion from one molecule of matter to the next.
3. The answer is; D
The sun rays (which are electromagnetic waves that travel in photons) travel from the sun and through the vacuum of space before they reach the earth. When the photons hit the molecules that make up your skin, they energize them and cause them to vibrate more energetically. As they, differentially, lose this kinetic energy (when resuming a lower excitation state), this energy is expended as heat which you feel on your face.
4. The answer is; D
To start with, it is important to note that water is not a good conductor of heat. Therefore, as it is heated from below by the Bunsen burner, the water at the bottom of the glass gets warmer that than at the top of the glass. Warm water is less dense than cool water hence begin to rise while the cooler water from the top replaces the rising warm water. This process continues and forms convection currents until the water starts to boil.
5. The answer is; B
When the can is opened, it exposes the soup to the environment. This way the heat from the soup (due to thermal disequilibrium) transfers from the soup to the air. Because the soup is hotter, it loses heat energy to the surrounding as dictated by laws of thermodynamics.
The citrus fruits are a good source of vitamin C.
The dark green leafy vegetables also have many important vitamins and minerals. They are an abundant source of vitamin C, A, K as well as (folate vitamin B9). Other than these, they also provide iron and calcium. The dark green leafy vegetables are also a great source of fibres. But, they are not very good source of ZINC or selenium.
hence, the correct answer is option A. Vitamin
<span>The strength of the gravitational force between two objects depends on two factors, mass and distance. the force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. increases, the force of gravity decreases.</span>
