The Symbol for a Certain Isotope of Strontium Is ${ } _ { 38 } ^ { 90 } \mathrm { Sr }$

question 140

Multiple Choice

The symbol for a certain isotope of strontium is ${ } _ { 38 } ^ { 90 } \mathrm { Sr }$ . What is the mass number of this isotope?

• A) 128
• B) 90
• C) 38
• D) 88
• E) 52

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Definitions:

T Wave

A feature on an electrocardiogram (ECG) representing the repolarization of the ventricles of the heart.

R Wave

Part of the QRS complex in an electrocardiogram (ECG) representing ventricular depolarization, which precedes ventricular contraction.

Heart Skeleton

A framework of dense connective tissue in the heart that provides structural support and attachment for cardiac muscle and valves.

Ectopic Stimuli

Electrical or chemical signals occurring at an abnormal location or time in the body, often resulting in irregular physiological responses such as ectopic heartbeats.