All checkbox are checked upon clicking

I'm fairly new to react, and I'm trying to create a simple form. The form app has many elements including the 3 checkbox. And to simplify my issue, I'm only showing the checkboxes. Here what I'm doing

1. When I click on a checkbox, the value of the label will be pushed into an array and saved into the App state.
2. I'm using event.target.name because I have multiple inputs in the form and I wanted to keep just in case to make my problem more descriptive.
3. When I click on submit, it should clear the checkbox.

The problem is when I click on checkbox all the 3 of get checked and it won't be cleared after hitting submit. Is there any way to overcome this? or why its happening?

function CheckBox(props) {
 var style= {
    padding:10,
    marginLeft:5
 }
  return(
    <div style={style} >
      {props.checkboxList.map((item,index) => 
        <div key={index}>
         <input type="checkbox" 
           onChange={props.changeHandler}
           checked={props.checkStatus} name={props.name} value={item.val} />
            <label>{item.num}) {item.val}</label>
        </div>)}

    </div>

    )
}

class App extends React.Component{
  constructor(props) {
    super(props);
    this.state={item:[],checked:false}
    this.changeHandler=this.changeHandler.bind(this)
    this.submitHandler=this.changeHandler.bind(this)
  }

changeHandler(event) {
  if(event.target.name=="choice") {    
  var arr=this.state.item.slice()
  arr.push(event.target.value)
  this.setState({item:arr, checked:event.target.checked}, ()=> console.log(this.state.item +"--"+ this.state.checked))
  }
  else{ console.log('error')}
}
  
 submitHandler(){
      this.setState({item:[],checked:false})
    }
  
render() {
  return(
  <div>
    <CheckBox  checkboxList={[
                {num:"a", val:"choice 1"},
                {num:"b", val:"choice 2"},
                {num:"c", val:"choice 3"}]} changeHandler={this.changeHandler} name="choice" checkStatus={this.state.checked} />
      <button onClick={this.submitHandler}>Submit</button>
    </div>
  )
}
}
ReactDOM.render(
  
  <App/>,
  
  document.getElementById("root")

)

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<div id="root"></div>