An atomic model shows 19 protons, 20 neutrons, and 19 electrons. What is the mass number of the atom?
A = 39
B = 58
C = 20
D = 19
The mass number of an atom is equal to the sum of its protons and neutrons. In this case, the atom has 19 protons and 20 neutrons, so the mass number is 19 + 20 = 39. Therefore, the correct answer is A = 39.
To create a molecular model, a student will use blue spheres to represent nitrogen (N) and white spheres to represent hydrogen (H). Which option correctly describes a model of ammonia, NH³?
A = one blue sphere and one white sphere
B = three blue spheres and one white sphere
C = three blue spheres and three white spheres
D = one blue sphere and three white spheres
The molecular formula for ammonia is NH₃, which means it consists of one nitrogen atom (N) and three hydrogen atoms (H). In the model, nitrogen is represented by blue spheres and hydrogen is represented by white spheres. Therefore, the correct option is D = one blue sphere and three white spheres.
A ball-and-stick model of a molecule of formaldehyde, CH²O, is made from the following components:
• one black ball
• one red ball
• two white balls
• three sticks
What do the sticks represent?
A= carbon atoms
B= hydrogen atoms
C= bonds between atoms
D= oxygen atoms
The sticks in a ball-and-stick model represent the bonds between atoms. In the molecule of formaldehyde (CH₂O), there is one carbon atom (C) represented by the black ball, two hydrogen atoms (H) represented by the white balls, and one oxygen atom (O) represented by the red ball. Therefore, the sticks in the model would represent the bonds between these atoms. Therefore, the correct answer is C= bonds between atoms.
Use the equation below to answer the question.
baking soda + vinegar = carbon dioxide + water + sodium acetate
which are the products in this equation?
A= sodium acetate only
B= baking soda, vinegar, carbon dioxide, water, and sodium acetate
C= baking soda and vinegar
D= carbon dioxide, and sodium acetate
The products in this equation are carbon dioxide, water, and sodium acetate.
Therefore, the correct answer is D= carbon dioxide and sodium acetate.