ProjectileFirer.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ProjectileFirer : MonoBehaviour
{

    public List<GameObject> projectilePrefabs;
    public float fireStrength = 20;
    public float spinStrength = 10f;

    void Start()
    {
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space) || Input.GetMouseButtonDown(0))
        {
            Fire();
        }
    }

    void Fire()
    {
        GameObject clone = Instantiate(Pick(projectilePrefabs), transform.position+transform.forward*2f, transform.rotation);
        Rigidbody rb = clone.GetComponent<Rigidbody>();
        rb.AddForce(transform.forward * fireStrength, ForceMode.Impulse);
        rb.AddTorque(Random.insideUnitSphere * spinStrength);
    }

    T Pick<T>(List<T> arr)
    {
        return arr[Random.Range(0, arr.Count)];
    }
}